Description of Leptopharynx bromelicola n. sp. and characterization of the genus Leptopharynx Mermod, 1914 (Protista, Ciliophora)

Using morphological, morphometrical, and molecular methods, we describe Leptopharynx bromelicola n. sp. from tank bromeliads of Jamaica. We add significant data to Leptopharynx costatus and briefly characterize and review the genus Leptopharynx Mermod, 1914, including four new combinations. Nine species can be distinguished when applying the following main features and assuming that most or all have the ability to produce macrostomes (MAs): distinct ridges along the right side ciliary rows; special features like spines or wings on the body and of the oral basket; dikinetids present vs. absent from somatic kinety 3; number of kinetids in kinety 6 as two for the costatus pattern and ≥ five for the bromelicola pattern; beginning and structure of kinety 9 as either underneath or far underneath the adoral membranelles and with or without dikinetids; postoral complex present vs. absent; and preoral kinety 4 continuous vs. discontinuous. The 18S rDNA sequences of L. bromelicola and L. costatus differ by 1.7% and show that Leptopharynx forms a distinct clade within the Nassophorea Small & Lynn, 1981. Leptopharynx bromelicola is possibly closely related to Leptopharynx euglenivora Kahl, 1926, which, however, lacks the basket nose so typical of the former. Leptopharynx forms thin-walled, non-kinetosome-resorbing resting cysts maintaining most of the trophic organelles.     

Nucleotide sequence determination of bacteriophage T4 glycine transfer ribonucleic acid

The nucleotide sequence of a T4 tRNA with an anticodon for glycine has been determined using ³²P-labeled material from T4-infected cultures of Escherichia coli. The sequence is: pGCGGAUAUCGUAUAAUGmGDAUUACCUCAGACUUCCAAψCUGAUGAUGUGAGTψCGAUUCUCAUUAUCCGCUCCA-OH. The 74 nucleotide sequence can be arranged in the classic cloverleaf pattern for tRNAs. The anticodon of T4 tRNA^Gly is UCC with a possible modification of the U. The tRNA molecule would thus be expected to recognize the glycine codons GGG and GGA. Comparative analysis of tRNAs^Gly from T2 and T6 indicate that their sequences are identical with that from T4.     

Pathological and immunological evaluation of different regimens of praziquantel treatment in a mouse model of Schistosoma mansoni infection

BackgroundOne of the considerable challenges of schistosomiasis chemotherapy is the inefficacy of praziquantel (PZQ) at the initial phase of the infection. Immature schistosomes are not susceptible to PZQ at the curative dose. Here, we investigated the efficacy of different PZQ regimens administered during the initial stage of Schistosoma mansoni infection in mice.Methodology/Principal findingsTwo months-old mice were individually infected with 80 S. mansoni cercariae and divided into one infected-untreated control group (IC) and four PZQ-treated groups: PZQ at 100 mg/kg/day for five consecutive days (group PZQ1), PZQ at 100 mg/kg/day for 28 days (group PZQ2), PZQ at 18 mg/kg/day for 28 days (group PZQ3) and a single dose of PZQ at 500 mg/kg (group PZQ4). The treatment started on day one post-infection (p.i), and each group of mice was divided into two subgroups euthanized on day 36 or 56 p.i, respectively. We determined the mortality rate, the parasitological burden, the hepatic and intestinal granulomas, the serum levels of Th-1, Th-2, and Th-17 cytokines, and gene expression. The treatment led to a significant (p < 0.001) reduction of worm burden and egg counts in the intestine and liver in groups PZQ2 and PZQ3. On 56^th day p.i, there was a significant reduction (p < 0.001) of the number and volume of the hepatic granulomas in groups PZQ2 and PZQ3 compared to group PZQ1 or PZQ4. Moreover, in group PZQ3, the serum levels of IFN-γ, TNF-α, IL-13, and IL-17 and their liver mRNA expressions were significantly reduced while IL-10 and TGF-β gene expression significantly increased. The highest mortality rate (81.25%) was recorded in group PZQ2.Conclusion/SignificanceThis study revealed that the administration of PZQ at 18 mg/kg/day for 28 consecutive days was the optimal effective posology for treating S. mansoni infection at the initial stage in a murine model.     

Distinct binding sites of Ala48-hirudin1-47 and Ala48-hirudin48-65 on alpha-thrombin

The interaction of alpha-thrombin with Ala48-hirudin, Ala48-hirudin1-47, and Ala48-hirudin48-65 was analyzed. Mutations at Pro48 were found to cause only slight changes in the kon (human: 3.1 +/- 0.3 x 10(8) M-1 s-1; bovine: 1.03 +/- 0.3 x 10(8) M-1 s-1) and koff (human: 0.4 +/- 0.2 x 10(-3) s-1; bovine: 2.9 +/- 0.4 x 10(-3) s-1) rate constants for the formation of the thrombin-hirudin complex. The amino-terminal fragment Ala48-hirudin1-47 containing the three disulfide bridges and the carboxyl-terminal fragment Ala48-hirudin48-65 were derived from the Ala48 mutant by proteolysis with endoproteinase Lys-C. These fragments inhibit bovine alpha-thrombin clotting activity with IC50 values of 0.6 and 4.9 microM, respectively (2.4 nM for r-hirudin). By mapping the interaction of Ala48-hirudin-derived fragments with bovine alpha-thrombin by limited proteolysis with trypsin and pancreatic elastase distinct binding sites for each fragment were determined. The carboxyl-terminal fragment was found to bind to the proposed anion-binding exosite in the region B62-74, whereas the amino-terminal fragment binds to a region around the elastase cleavage site at residues 150-151 of the alpha-thrombin B-chain.     

Extraction and fractionation of complex lipid mixtures with dense carbon dioxide on a micro scale

The effects of pressure, temperature and some organic solvents on the recovery of various lipid classes from plant and animal tissues can be assessed by fractional extraction with dense carbon dioxide and consecutive analysis by thin-layer chromatography.