Regulation of l-ornithine decarboxylase and S-adenosyl-l-methionine decarboxylase in rat ventral prostate and seminal vesicle

1. The activities of l-ornithine decarboxylase (EC 4.1.1.17) and S-adenosyl-l-methionine decarboxylase (EC 4.1.1.50) were dramatically enhanced in both the ventral prostate and the seminal vesicle of castrated rats in response to androgenic stimulation. The time course of the stimulation of ornithine decarboxylase together with the quantitatively different response of adenosylmethionine decarboxylase to testosterone treatment in the prostate gland and seminal vesicle indicated that the enhancement in polyamine synthesis in the ventral prostate may reflect both cellular proliferation and the restoration of the secretory functions of the organ. In the seminal vesicle, however, the stimulation of the polyamine-biosynthetic pathway more closely resembled the pattern found in other rat tissues, such as regenerating liver, undergoing compensatory growth. 2. Ornithine decarboxylase activity in the ventral prostate and especially in the seminal vesicle of sexually mature rat was diminished in vivo by various short-chain diamines such as 1,2-diaminoethane, 1,3-diaminopropane and putrescine (1,4-diaminobutane). These diamines had no direct effect on the enzyme activity in vitro. 3. In contrast with the marginal decrease in ornithine decarboxylase activity produced by diaminoethane in the ventral prostate of non-castrated animals, repeated injections of the latter amine completely prevented the intense stimulation of the enzyme activity in the ventral prostate and seminal vesicle of castrated rats at 24h after the commencement of testosterone treatment. 4. The decrease in ornithine decarboxylase activity observed after injections of diamines (putrescine) in the ventral prostate was apparently associated with a similar decrease in the amount of immunoreactive protein as revealed by immunotitration of the enzyme with antiserum to rat ornithine decarboxylase.     

Production of endo-1,4-β-glucanase and xylanase by Trichoderma reesei immobilized on polyurethane foam

Summary Endo-1,4--glucanase and xylanase were produced by Trichoderma reesei immobilized on polyurethane foam using lactose as the main carbon source. The most porous carrier was found to be the best of those tested. The nitrogen source and KH₂PO₄ concentration of the production medium had a marked effect on culture pH during the course of fermentation and, consequently, on xylanase activity. An increase in lactose concentration from 7 to 27 g/l resulted in an increase in endoglucanase activity (max. 730 U/ml), xylanase activity (max. 3350 U/ml) and filter paper activity (max. 3.0 FPU/ml).     

Polyamine deprivation causes major chromosome aberrations in a polyamine-dependent Chinese hamster ovary cell line

This paper describes the effects of polyamine deprivation on chromosomes of a polyamine-dependent Chinese hamster ovary cell line which grows continuously in serum-free medium. After 6 days' polyamine deprivation the number of mitoses decreased drastically and most of them showed major chromosome aberrations. There were several gaps and breaks in many chromosomes, some cells exhibiting extensive chromosome fragmentation. Elongation of chromosomes, indicative for unpacking of the chromosome fibres, were also seen. The time course of Harlequin staining of the chromosomes revealed prolongation of the cell cycle in the polyamine-starved cells. The mean number of sister chromatid exchanges per cell was a little higher in the polyamine-starved than in the control cells. The difference is statistically significant, but it has to be taken with some caution, because the experiments could not be carried out under strictly comparable conditions.     

Activin-A, but not inhibin, regulates 17β-hydroxysteroid dehydrogenase type 1 activity and expression in cultured rat granulosa cells

17β-Hydroxysteroid dehydrogenase type 1 (17HSD type 1) catalyzes the reduction of estrone (E₁) to biologically more active estradiol (E₂). In the present study, the effect of activin, inhibin, and follistatin on 17HSD activity and 17HSD type 1 expression in cultured, unluteinized rat granulosa cells was examined. Furthermore, the effects of these hormones on 17HSD type 1 expression were compared with the expression of P450 aromatase (P450arom). Rat granulosa cells were pre-incubated in serum-free media for 3 days, followed by a 2-day treatment with activin, inhibin, follistatin and 8-Br-cAMP. Activin in increasing concentrations appeared to effect a dose-dependent increase in 17HSD activity. In addition, increasing concentrations of activin also increased 17HSD type 1 mRNA expression. Addition of 8-Br-cAMP at concentrations of 0.25 and 1.5 mmol/l together with activin significantly augmented the stimulatory effects of activin alone in the cultured cells. Neither inhibin, nor follistatin, either alone or in combination with 8-Br-cAMP, had any notable effects on 17HSD activity and 17HSD type 1 expression. Preincubation of activin with increasing concentrations of follistatin significantly diminished the stimulatory effect of activin. In the presence of follistatin, activin did not significantly increase the 8-Br-cAMP-induced 17HSD activity and 17HSD type 1 expression. The culturing of granulosa cells in the presence or the absence of inhibin or follistatin with or without 8-Br-cAMP did not alter the effect of these peptides on P450arom expression in rat granulosa cells as judged by Northern blot analysis of total RNA. However, cAMP-induced P450arom expression was enhanced by activin treatment, except when follistatin was present. This is in line with the suggested role of follistatin as an activin-binding protein, which limits the bioavailability of activin to its membrane receptors. Thus, the results support the notion of a paracrine/autocrine role of activin in follicular steroidogenesis of growing follicles.     

Constructed deletions in lumen-exposed regions of the D1 protein in the cyanobacterium Synechocystis 6803: Effects on D1 insertion and accumulation in the thylakoid membrane, and on Photosystem II assembly

Modified forms of the D1 protein with deletions in lumen-exposed regions, were constructed in the cyanobacterium Synechocystis 6803 using site-directed mutagenesis. Integration and stability of the mutated D1 proteins in the thylakoid membrane were studied by immunoblot and pulse-chase analyses. It was found that in (N325-E333), the D1 protein with a deletion in the C-terminal tail, could insert in the thylakoids to normal amounts but its stability in the membrane was dramatically reduced. Insertion of D1 in (V58-D61) or (D103-G109);G110R, with deletions in the A-B loop, was severely obstructed, For (P350-T354), with a deletion in the processed region of the C-terminus of D1, no phenotypic effects were observed. The effects of failed D1 insertion or accumulation on Photosystem II assembly was monitored by immunoblot analysis. The conclusions from these experiments are that the extrinsic 33 kDa protein, CP43, and the subunit of cytochrome b559 accumulate in the thylakoid membrane independently of the D1 protein, and that accumulation of the D2 protein and CP47 requires insertion but not necessarily accumulation of the D1 protein.Abbreviations PSI II Photosystem II - PCR Polymerase Chain reaction Present address: Université Joseph Fourier, Sciences Technologie Médecine, BP 53, 38041 Grenoble Cedex 9, France     

Estimation of reference conditions for phytoplankton in a naturally eutrophic shallow lake

Classification of waters using biological quality elements and determination of the degree of deviation from reference levels is a key issue in the Water Framework Directive of EU. Lakes in reference conditions with sufficient biological data are available for several boreal lake types with the exception of naturally eutrophic lakes. An empirical approach is one alternative for estimating the reference conditions of such lakes. We used the water transparency of the naturally eutrophic Lake Tuusulanjärvi recorded in August in the early 1910s to estimate reference values for phytoplankton biomass and chlorophyll a concentrations. Three phytoplankton samples during August 2000–2001 corresponded to the estimated reference values for total biomass (<5.6 mg l^?1) and chlorophyll a (<28 μg l^?1), as did the simultaneous Secchi depths. The phytoplankton assemblage in these samples with 24 eutrophy indicators (17% of the total taxa number) corresponded in general the species list from the early 1900s, which as such could be regarded as reference assemblage. Furthermore, in August 2000, 3 years after intensive fish removal a prominent decrease in cyanobacterial biomass and toxin concentration was observed. The costs of the measures and studies in Lake Tuusulanjärvi during 1989–2003 have been approximately 2.5 million euros.     

Identification of a sudden cardiac death susceptibility locus at 2q24.2 through genome-wide association in European ancestry individuals

Sudden cardiac death (SCD) continues to be one of the leading causes of mortality worldwide, with an annual incidence estimated at 250,000–300,000 in the United States and with the vast majority occurring in the setting of coronary disease. We performed a genome-wide association meta-analysis in 1,283 SCD cases and >20,000 control individuals of European ancestry from 5 studies, with follow-up genotyping in up to 3,119 SCD cases and 11,146 controls from 11 European ancestry studies, and identify the BAZ2B locus as associated with SCD (P = 1.8×10⁻¹⁰). The risk allele, while ancestral, has a frequency of ∼1.4%, suggesting strong negative selection and increases risk for SCD by 1.92–fold per allele (95% CI 1.57–2.34). We also tested the role of 49 SNPs previously implicated in modulating electrocardiographic traits (QRS, QT, and RR intervals). Consistent with epidemiological studies showing increased risk of SCD with prolonged QRS/QT intervals, the interval-prolonging alleles are in aggregate associated with increased risk for SCD (P = 0.006).     

The PsbZ subunit of Photosystem II in Synechocystis sp. PCC 6803 modulates electron flow through the photosynthetic electron transfer chain

The psbZ gene of Synechocystis sp. PCC 6803 encodes the ∼6.6 kDa photosystem II (PSII) subunit. We here report biophysical, biochemical and in vivo characterization of Synechocystis sp. PCC 6803 mutants lacking psbZ. We show that these mutants are able to perform wild-type levels of light-harvesting, energy transfer, PSII oxygen evolution, state transitions and non-photochemical quenching (NPQ) under standard growth conditions. The mutants grow photoautotrophically; however, their growth rate is clearly retarded under low-light conditions and they are not capable of photomixotrophic growth. Further differences exist in the electron transfer properties between the mutants and wild type. In the absence of PsbZ, electron flow potentially increased through photosystem I (PSI) without a change in the maximum electron transfer capacity of PSII. Further, rereduction of P700⁺ is much faster, suggesting faster cyclic electron flow around PSI. This implies a role for PsbZ in the regulation of electron transfer, with implication for photoprotection.