Excitation energy transfer from phycobiliprotein to chlorophyll d in intact cells of Acaryochloris marina studied by time- and wavelength-resolved fluorescence spectroscopy.

The fluorescence decay spectra and the excitation energy transfer from the phycobiliproteins (PBP) to the chlorophyll-antennae of intact cells of the chlorophyll (Chl) d-dominated cyanobacterium Acaryochloris marina were investigated at 298 and 77 K by time- and wavelength-correlated single photon counting fluorescence spectroscopy. At 298 K it was found that (i) the fluorescence dynamics in A. marina is characterized by two emission peaks located at about 650 and 725 nm, (ii) the intensity of the 650 nm fluorescence depends strongly on the excitation wavelength, being high upon excitation of phycobiliprotein (PBP) at 632 nm but virtually absent upon excitation of chlorophyll at 430 nm, (iii) the 650 nm fluorescence band decayed predominantly with a lifetime of 70 +/- 20 ps, (iv) the 725 nm fluorescence, which was observed independent of the excitation wavelength, can be described by a three-exponential decay kinetics with lifetimes depending on the open or the closed state (F(0) or F(m)) of the reaction centre of Photosystem II (PS II). Based on the results of this study, it is inferred that the excitation energy transfer from phycobiliproteins to Chl d of PS II in A. marina occurs with a time constant of about 70 ps, which is about three times faster than the energy transfer from the phycobilisomes to PS II in the Chl a-containing cyanobacterium Synechococcus 6301. A similar fast PBP to Chl d excitation energy transfer was also observed at 77 K. At 77 K a small long-lived fluorescence decay component with a lifetime of 14 ns was observed in the 640-700 nm spectral range. However, it has a rather featureless spectrum, not typical for Chl a, and was only observed upon excitation at 400 nm but not upon excitation at 632 and 654 nm. Thus, this long-lived fluorescence component cannot be used as an indicator that the primary PS II donor of Acaryochloris marina contains Chl a.     

Development of a diploid cell line from fetal rhesus monkey lung for virus vaccine production

Summary The primary goal of this study was to develop and characterize diploid cell lines from fetal tissues of subhuman primates for use in virus vaccine production. Cell lines have been established from fetal tissues of rhesus and African green monkeys, and these have been characterized according to the general criteria recommended by the International Cell Committee for Microbiological Standardization. Of these cell lines, DBS-FRhL-2, developed from lung tissue of a rhesus monkey fetus, has been found to meet the requirements of populations proposed as substrates for virus vaccines. Characterization studies show that DBS-FRhL-2 cells have a finite life of more than 50 population doublings in vitro and maintain the diploid karyotype through an active growth phase. The cells are nontumorigenic, and tests have not revealed the presence of adventitious agents. They are susceptible to a number of human viruses and can be preserved by freezing without change in virus susceptibility, cytogenetic, or growth characteristics. These results indicate the need for further evaluation of this rhesus monkey diploid cell line for acceptability as an alternate substrate in the manufacture of human virus vaccines. The research upon which this publication is based was performed pursuant to Contract No. NIH-69-100 with the Division of Biologics Standards of the National Institutes of Health.     

Apoptosis and inhibition of gap-junctional intercellular communication induced by LA-12, a novel hydrophobic platinum(IV) complex

A new hydrophobic platinum(IV) complex, LA-12, a very efficient anticancer drug lacking cross-resistance with cisplatin (CDDP), is now being tested in clinical trials. Here we investigated the apoptogenic activity of LA-12 and its effect on gap-junctional intercellular communication (GJIC) in the rat liver epithelial cell line WB-F344. LA-12 induced apoptosis much more efficiently than did CDDP due to a combination of rapid penetration into the cell and attack on DNA, leading to fast activation of p53 and caspase-3. Exposure of WB-F344 cells to LA-12 led to rapid induction of the time- and dose-dependent decrease in GJIC. On the molecular level, loss of GJIC induced by LA-12 was mediated by activation of extracellular signal-regulated kinase (ERK)-1 and ERK-2, as demonstrated by the use of inhibitors of ERK activation. Inhibition of GJIC was linked to rapid hyperphosphorylation of connexin-43 and disappearance of connexon clusters from membranes, which was not observed in the case of CDDP.     

Lipase B from Candida antarctica catalyses enantioselective transesterification of 2-(4-methoxybenzyl)-1-cyclohexanols and 2-(4-methoxybenzyl)-1-cyclopentanols

The 2-(4-methoxybenzyl)-1-cyclohexanols and 2-(4-methoxybenzyl)-1-cyclopentanols are the basic structure of a series of juvenile hormone analogs which act as insect growth regulators. Their enantioselective transesterification with the lipase B from Candida antarctica produced pure enantiomers of R-cyclohexyl and R-cyclopentyl acetates (i.e. ee_p > 99%). Differences observed in the resolution of the four racemic compounds are in accordance with model structure of secondary alcohols suitable for catalysis.     

Lasioglossins LLIII affect the morphogenesis of Candida albicans and reduces the duration of experimental vaginal candidiasis in mice

Lasioglossins are a group of peptides with identified antimicrobial activity. The inhibitory effects of two synthetic lasioglossin derivatives, LLIII and D‐isomeric variant LLIII‐D, on morphological changes in Candida albicans in vitro and the effect of local administration of LLIII during experimental murine candidiasis were investigated. C. albicans blastoconidia were grown in the presence of lasioglossin LLIII or LLIII‐D at concentrations of 11.5 μM and 21 μM, respectively, for 1, 2 and 3 days and their viability determined by flow cytometry using eosin Y staining. Morphological changes were examined by light and fluorescent microscopy. The Candida‐inhibitory effect of daily intravaginal administration of 0.7 or 1.4 μg of LLIII was assessed in mice with experimentally‐induced vaginal candidiasis. LLIII and LLIII‐D lasioglossins exhibited candidacidal activity in vitro (>76% after 24 hr and >84% after 48 hr of incubation). After 72 hr incubation of Candida with low concentration of lasioglossins, an increase in viability was detected, probably due to a Candida antimicrobial peptides evasion strategy. Furthermore, lasioglossins inhibited temperature‐induced morphotype changes toward hyphae and pseudohyphae with sporadic occurrence of atypical cells with two or enlarged nuclei, suggesting interference with mitosis or cytokinesis. Local application of LLIII reduced the duration of experimental candidiasis with no evidence of adverse effects. Lasioglossin LLIII is a promising candidate for development as an antimicrobial drug for treating the vaginal candidiasis.

     

Morphological and molecular characterization of a spontaneously tuberizing potato mutant: an insight into the regulatory mechanisms of tuber induction

Background  

Tuberization in potato (Solanum tuberosum L.) represents a morphogenetic transition of stolon growth to tuber formation, which is under complex environmental and endogenous regulation. In the present work, we studied the regulatory mechanisms and the role of different morphogenetic factors in a newly isolated potato mutant, which exhibited spontaneous tuberization (ST). The ST mutant was characterized in detail at morphological, physiological and biochemical levels.     

Hazard function for cancer patients and cancer cell dynamics

The aim of the paper is to develop a procedure for an estimate of an analytical form of a hazard function for cancer patients. Although a deterministic approach based on cancer cell population dynamics yields the analytical expression, it depends on several parameters which should be estimated. On the other hand, a kernel estimate is an effective nonparametric method for estimating hazard functions. This method provides the pointwise estimate of the hazard function. Our procedure consists of two steps: in the first step we find the kernel estimate of the hazard function and in the second step the parameters in the deterministic model are obtained by the least squares method. A simulation study with different types of censorship is carried out and the developed procedure is applied to real data.     

Marburg variant multiple sclerosis - a case report

In this case report we describe the case of a 24 year-old female with a fulminant demyelinating disease of white matter. Disease progression was most probably consistent with the Marburg variant (malignant form) of multiple sclerosis with rapid deterioration of the patient's clinical condition, including bulbar symptoms and epileptic paroxysms and ending with persistent coma and tetraparesis, over the course of 6 months from first symptoms. Repeated Magnetic Resonance Imaging (MRI) examination showed progression of multiple demyelinating lesions culminating in a contiguous focal disorder of the white matter extending both supratentorially and infratentorially. The serial MRI changes closely mapped the deterioration in the patients clinical status. Our patient showed no response to repeated pulse corticotherapy, administration of intravenous immunoglobulins, serial plasmapheresis, and combined high-dose pulse immunosuppression (specify what was used here) and mitoxantrone.