The control of Monomorium pharaonis (Hymenoptera: Formicidae) with Bacillus thuringiensis

In this study, the effect of different preparations made from Bacillus thuringiensis var. thuringiensis (strains: CCEB 555 and CCEB 058) on ants, Monomorium pharaonis, under laboratory conditions is reported. The different preparations tested consisted of (1) a liquid culture of the strain B. thuringiensis CCEB 555 (containing spores and exotoxin), (2) the supernatant of the culture broth of strain CCEB 555 (containing exotoxin), and (3) the biological preparation “Bathurin” prepared from the strain B. thuringiensis CCEB 058 (containing spores and inclusions, without exotoxin). The preparations were used either pure or in alternation with borax, i.e., 1 wk borax, 3 wk the respective preparation for several months. All preparations were found to be toxic to M. pharaonis and their effect was characterized by a slow extinction of the ant colony. Administration of “Bathurin” (1.3%) yielded a 100% mortality after 20 wk. Using a liquid culture of B. thuringiensis var. thuringiensis, 100% mortality was recorded after 21 wk, a period of time which did not differ from that obtained with the supernatant of the culture containing exotoxin. The alternation with borax was found to accelerate ant mortality by 9–10 wk after administration. In all experiments, the worker ants died first, the queen ants surviving them by 1–3 wk.In experiments employing worker ants only, a 100 and 98% mortality, respectively, occurred within 3 wk after administration of a liquid culture of B. thuringiensis and “Bathurin” supplemented with borax.     

Saurian malaria in the Caribbean: Plasmodium azurophilum sp. nov., a malarial parasite with schizogony and gametogony in both red and white blood cells

A survey of 466 Caribbean lizards found Plasmodium parasites present in Anolis species only of five islands. Parasites presently considered to be P. floridense occurred on Grand Cayman, North Bimini, Jamaica, Hispaniola (Haiti), and Puerto Rico. A second species, P. azurophilum, is described as new from Anolis cybotes of Haiti, A. krugi of Puerto Rico, and A. lineatopus and A. grahami of Jamaica. It lacks visible pigment in erythrocytic host cells but can produce it occasionally. Both asexual and sexual forms occur in a variety of white blood cells, notably in azurophil granulocytes and polymorphonuclear leucocytes. Experimental infections indicate that the leucocytic phase occurs after the acute erythrocytic infection declines, thus suggesting that the schizogonic and gametogonic cycles in white cells may represent an adaptive defense against immune mechanisms of the host. Mean numbers of nuclei in schizonts and mean gametocyte size are influenced by host species and type of host cell.     

Role of adenosine 3′:5′-cyclic monophosphate in the action of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT) on hepatic and renal metabolism

The possibility whether alterations in the cyclic AMP-adenylate cyclase-phosphodiesterase system play a role in the action of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (DDT) on hepatic and renal carbohydrate metabolism was investigated. Administration of exogenous cyclic AMP (10mg/100g) was found to mimic the action of DDT which enhanced the activities of pyruvate carboxylase, phosphoenolpyruvate carboxylase, fructose 1,6-diphosphatase and glucose 6-phosphatase in both liver and kidney cortex, elevated the concentration of blood glucose and urea and decreased the amount of hepatic glycogen. Treatment with theophylline augmented the effects of a submaximal dose of this halogenated hydrocarbon on serum urea and glucose as well as the key gluconeogenic enzymes in liver and kidney cortex. Addition of DDT in vitro to liver and kidney homogenates resulted in a significant enhancement of adenylate cyclase activity. Hepatic and renal slices from rats already treated with DDT displayed an increased ability to convert [(3)H]adenosine into cyclic [(3)H]AMP. Whereas kidney-cortex slices excised from rats given caffeine and DDT produced an even greater amount of cyclic [(3)H]AMP, imidazole, propranolol and hydrazine prevented the insecticide-stimulated rise in cyclic nucleotide production. In contrast, prostaglandin E(1) failed to exert any significant effect on DDT-induced increases in cyclic [(3)H]AMP synthesis from radioactive adenosine. The present study and our previous findings (Kacew & Singhal, 1973e) support the concept that the DDT-induced alterations in carbohydrate metabolism of liver and kidney cortex may be related to an initial stimulation of the cyclic AMP-adenylate cyclase system in these tissues.     

“Capillary Permeability” in Patients with Collagen Vascular Diseases

“Capillary permeability” to serum albumin has been measured in patients with collagen vascular diseases by a method which compares the dilution of intravenously injected ¹³¹I-human serum albumin and ⁵¹Cr-R.B.C.s. The results indicate an increased capillary permeability comparable to that which occurs in patients with extensive inflammatory skin disease. We suggest that this increased capillary permeability may be the cause of the episodes of oedema which occur in patients with collagen vascular diseases such as disseminated lupus erythematosus, systemic sclerosis, dermatomyositis, polyarteritis nodosa, and rheumatoid arthritis. “Spontaneous periodic oedema” may be the presenting feature of collagen vascular disease and is due to increased capillary permeability.     

The characterization of human uterine smooth muscle cells in culture

Primary cultures initiated from normal human uterine endometrium after total enzymatic dissociation contained epithelioid cells and smooth muscle cells. The smooth muscle cells were subsequently isolated by differential trypsinization and grown in culture for 36 +/- 4 generations. Ultrastructural examination of log and post-confluent cultures of cells at low and high population doubling levels revealed characteristics similar to those of published reports on other smooth muscle cells studied in vivo and in vitro. Among the common features present were: (a) abundant bundles of 60--70 A myofilaments; (b) branched mitochondria; (c) stacks of cisternae of rough endoplasmic reticulum; (d) caveolae intracellulares; (e) nexuses. Other features included ovoid nuclei, a well developed Golgi apparatus and abundant free ribosomes. The subcultured cells exhibited features of dedifferentiation in the log phase of growth and at post-confluency. However, the post-confluent cells showed characteristics indicating redifferentiation back towards their in vivo morphology. Smooth muscle cells isolated from endometrial curettings may provide a useful model for biochemical and pharmacological studies of a cell type derived from a hormonal target tissue as the cells "age" in culture.     

A family of phosphodiesterase inhibitors discovered by cocrystallography and scaffold-based drug design

Cyclic nucleotide phosphodiesterases (PDEs) comprise a large family of enzymes that regulate a variety of cellular processes. We describe a family of potent PDE4 inhibitors discovered using an efficient method for scaffold-based drug design. This method involves an iterative approach starting with low-affinity screening of compounds followed by high-throughput cocrystallography to reveal the molecular basis underlying the activity of the newly identified compounds. Through detailed structural analysis of the interaction of the initially discovered pyrazole carboxylic ester scaffold with PDE4D using X-ray crystallography, we identified three sites of chemical substitution and designed small selective libraries of scaffold derivatives with modifications at these sites. A 4,000-fold increase in the potency of this PDE4 inhibitor was achieved after only two rounds of chemical synthesis and the structural analysis of seven pyrazole derivatives bound to PDE4B or PDE4D, revealing the robustness of this approach for identifying new inhibitors that can be further developed into drug candidates.     

Biochemical and genomic analysis of substrate recognition by the double-stranded RNA binding domain of yeast RNase III

Members of the RNase III family of double-stranded RNA (dsRNA) endonucleases are important enzymes of RNA metabolism in eukaryotic cells. Rnt1p is the only known member of the RNase III family of endonucleases in Saccharomyces cerevisiae. Previous studies have shown that Rnt1p cleaves dsRNA capped by a conserved AGNN tetraloop motif, which is a major determinant for Rnt1p binding and cleavage. The solution structure of the dsRNA-binding domain (dsRBD) of Rnt1p bound to a cognate RNA substrate revealed the structural basis for binding of the conserved tetraloop motif by alpha-helix 1 of the dsRBD. In this study, we have analyzed extensively the effects of mutations of helix 1 residues that contact the RNA. We show, using microarray analysis, that mutations of these amino acids induce substrate-specific processing defects in vivo. Cleavage kinetics and binding studies show that these mutations affect RNA cleavage and binding in vitro to different extents and suggest a function for some specific amino acids of the dsRBD in the catalytic positioning of the enzyme. Moreover, we show that 2'-hydroxyl groups of nucleotides of the tetraloop or adjacent base pairs predicted to interact with residues of alpha-helix 1 are important for Rnt1p cleavage in vitro. This study underscores the importance of a few amino acid contacts for positioning of a dsRBD onto its RNA target, and implicates the specific orientation of helix 1 on the RNA for proper positioning of the catalytic domain.     

A new algorithm for detecting low-complexity regions in protein sequences

MOTIVATION: Pair-wise alignment of protein sequences and local similarity searches produce many false positives because of compositionally biased regions, also called low-complexity regions (LCRs), of amino acid residues. Masking and filtering such regions significantly improves the reliability of homology searches and, consequently, functional predictions. Most of the available algorithms are based on a statistical approach. We wished to investigate the structural properties of LCRs in biological sequences and develop an algorithm for filtering them. RESULTS: We present an algorithm for detecting and masking LCRs in protein sequences to improve the quality of database searches. We developed the algorithm based on the complexity analysis of subsequences delimited by a pair of identical, repeating subsequences. Given a protein sequence, the algorithm first computes the suffix tree of the sequence. It then collects repeating subsequences from the tree. Finally, the algorithm iteratively tests whether each subsequence delimited by a pair of repeating subsequences meets a given criteria. Test results with 1000 proteins from 20 families in Pfam show that the repeating subsequences are a good indicator for the low-complexity regions, and the algorithm based on such structural information strongly compete with others. AVAILABILITY: http://bioinfo.knu.ac.kr/research/CARD/ CONTACT: swshin@bioinfo.knu.ac.kr