The reproductive behaviour of a clonal herbaceous plant, the longleaved sundew Drosera intermedia, in different heathland habitats

The reproductive behaviour of the longleaved sundew Drosera intermedia Hayne was studied in three hydrologically differing heathland habitats a pool edge, an old path through the wet heath and a seepage area
Sexual reproductive allocation (SRA) (the slope of the regression of sexual biomass on vegetative biomass m a given season) differed strongly between years (related to temperature and precipitation) and habitats Averaged over years, path plants had a higher SRA than plants in the seepage area and at the pool edge
Asexual reproductive allocation, expressed as the size-dependent probability of reproducing asexually, did not differ between habitats in most years
The observations agreed with general life history theory SRA was high in the path habitat where adult survival chances were low and juvenile (= seed, first year seedling) survival was high SRA was lower in the seepage area where adult survival chances were higher and juvenile survival lower At the pool edge, a habitat with high adult mortality and low juvenile establishment, the predicted optimal reproductive behaviour, a high SRA, was not observed due to environmental constraints (inundation)     

Platelet activating factor induces expression of early response genes c-fos and TIS-1 in human epidermoid carcinoma A-431 cells

The effect of platelet activating factor (PAF) on the induction of early response genes was investigated in A-431 cells (human epidermal carcinoma cells). PAF induced a transient expression of c-fos and TIS-1 mRNA in a time- and dose-dependent manner. As low as 10(-10) M PAF caused detectable expression of these genes with a maximum observed at 10(-7) M. In the presence of cycloheximide, increases in the gene expression were noticeable at 20 min and peaked between 30-60 min. A lack of induction with lyso-PAF, an inactive PAF metabolite, confirmed the specificity of PAF towards this expression. The cells pretreated with CV-6209, a PAF receptor antagonist, did not show any induction of these genes by PAF. It is concluded that PAF causes induction of the early response genes c-fos and TIS-1 in a structurally specific and receptor dependent manner. This finding offers a new role for PAF at the nuclear level and may have important implications in the long term effects of PAF in pathophysiological conditions.     

Some factors that influence the plasma lipoprotein 1H NMR spectra of normal and cancer patients: an oncolipid test?

Selected factors have been evaluated in order to determine their influences on the plasma lipoprotein proton NMR spectra of normal and cancer patients. The variables were donor''s diet (fasting/non-fasting), temperature and time of sample storage, processing procedure, centrifugation speed, and water pre-saturation time. Plasma samples from fasting individuals that were placed immediately on ice, spun at 1,000 and 3,000 g for 15 minutes, and the proton NMR spectrum acquired with the Carr-Purcell Meiboom-Gill (CPMG) pulse sequence, using a two-second water pre-saturation time, consistently gave reproducible results. Resonances attributed to lactate were minimized under these processing conditions. Centrifugation speed and pre-saturation time did not affect the average line width; however, donor fasting state, processing temperature, and storage time did alter the line width. Most important, blood chemistry analysis revealed an inverse correlation between triglyceride levels and average methyl and methylene line widths. Thus, these factors alone caution against the indiscriminate use of proton NMR spectra to differentiate plasma from normal and cancer patients.     

Three new species of Bychowskyella Achmerow, 1952 (Monogenea) from Peninsular Malaysia

Three new and one previously described species of Bychowskyella Achmerow, 1952 were collected from the gills of four species of freshwater catfish in Peninsular Malaysia. They are Bychowskyella teysmanni n. sp. from Clarias teysmanni (Bleeker, 1857) (Clariidae), Bychowskyella sisoris n. sp. from Glyptothorax major (Boulenger, 1894) (Sisoridae), Bychowskyella baueri n. sp. from Silurichthys hasselti (Bleeker, 1858) (Siluridae), and Bychowskyella tchangi Gussev, 1976 from Clarias macrocephalus Gunther, 1864 (Clariidae). B. teysmanni n. sp. differs from B. tchangi in having two pairs of large marginal hooks. B. sisoris n. sp. is unique in possessing two onchia, while B. baueri n. sp. differs from previously described Bychowskyella species in the structure of the dorsal onchium. C. macrocephalus is a new host record for B. tchangi in Peninsular Malaysia.     

Purification and properties of intracellular fructosyl transferase fromAureobasidium pullulans

Intracellular frustosyl transferase was purified fromAureobasidium pullulans C-23 by ethanol fractionation, CM-Sephadex chromatography and preparative disc gel electrophoresis. It was shown to be homogeneous on disc polyacrylamide gel electrophoresis, with a molecular size of 190kDa. The pI value of the enzyme was about 3.7. The enzyme has aK _m value of 0.43 mM for sucrose and was optimally active at pH 5.0 and 60°C. The enzyme was stable from pH 2.5 to 12. It was almost completely inhibited by 5mM Hg²⁺ but was not significantly affected by other cations. The transferase was inactivated by treatment with the tryptophan-specific reagentN-bromosuccinimide and the tyrosine-specific reagent, I₂, suggesting that tryptophan and tyrosine residues are probably located at or near the active site of the enzyme.     

Audit of compliance with antenatal protocols.

OBJECTIVE--To assess the implementation of action protocols dictated by antenatal risk factors noted at the initial (booking) antenatal visit. DESIGN--Retrospective study of 2000 women delivered between 1 March 1990 and 29 March 1991. SETTING--Maternity department of a district general hospital supporting a multiethnic population in inner London. MAIN OUTCOME MEASURES--Comparison of clinical actions performed against those dictated by the department''s protocols. Analysis according to clinical importance, gestation at booking, maternal age, parity, birth order, ethnic origin, and certainty of gestational age. RESULTS--Interobserver agreement between the two auditors was good (kappa statistic for risk factors detected, 0.78; for actions generated, 0.80). Of the 15,658 actions dictated by department protocols, 3673 (23.5%) were actually performed by the clinicians. The 63 combinations of risk factors and actions believed by consultants to be of particular clinical importance had an action rate of 28.3% compared with 18.6% for those considered less important (p < 0.001). Mothers who first visited the hospital antenatal clinic at or before 24 weeks'' gestation had 25.2% of relevant protocols fulfilled (p < 0.001). Compliance was significantly improved in women aged 36 or over (32.4%), black women (24.9%), and cases of uncertain gestation (24.5%). Parity and birth order were not associated with an altered action rate. Ethnic origin deemed as "other" (than white, black, Asian, or oriental) or "unknown" was associated with poor compliance (19.3%). CONCLUSIONS--Compliance to a set of agreed protocols was poor even though a computer system was available and a protocol manual had been distributed. Protocols were more likely to be implemented in women who booked early and in some groups of women deemed at high risk including older mothers, black women, and those denoted as having uncertain gestational age.     

Carbonisation of oil palm trunks at moderate temperatures

Thousands of tonnes of dry oil palm trunks will be produced annually in Malaysia after about 1990. A project was initiated to study the feasibility of converting palm trunks into charcoal. Carbonisation was done at terminal temperatures of 400–550°C with holding times of 1–3 h and at two heating rates. From laboratory-scale pyrolysis studies, it was found that holding time does not affect the quantity and quality of the charcoal produced, while heating rate has a minor influence. However, as terminal temperature increases, both yield and volatile content decrease while the fixed carbon content increases. The calorific value and ash contents are independent of the parameters studied and their respective values are 4032 kcal/kg and 37.2%. Since the calorific value is low and the ash content high, it is concluded that oil palm trunks are not suitable for the production of charcoal fuel.     

Lymphocyte activation and serine-esterase induction following recombinant interleukin-2 infusion for lymphomas and acute leukaemias

Summary C57BL mice inoculated with radiation leukemia virus (RadLV) develop preleukemic cells long before the onset of leukemia. These cells are potentially immunogenic but fail to elicit an immune response in the host because of the appearance of virus-specific suppressor T cells. We have studied the effect of polysaccharide K (PSK) on the generation of RadLV-specific cell-mediated immune responses in vitro. Long-term exposure to PSK in culture potentiated the ability of immunized T cells to respond to a RadLV-induced lymphoma. It also abrogated the suppressive activity of suppressor T cells and simultaneously boosted the ability of reactive T cells to respond. The dual immunostimulating activity of PSK resulted in the generation of T cytotoxic lymphocytes that could lyse lymphoma cells in vitro. The results suggest that PSK could be used as a prophylactic immune response modifier in preleukemia.     

Reaction of pyruvate kinase with the new nucleotide affinity labels 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 5'-diphosphate and 5'-triphosphate

Two new reactive nucleotides have been synthesized and characterized: 8-[(4-bromo-2,3-dioxobutyl)thio]adenosine 5'-diphosphate and 5'-triphosphate (8-BDB-TADP and 8-BDB-TATP). ADP or ATP was converted to 8-thio-ADP (-ATP) via 8-bromo-ADP (-ATP), followed by condensation with 1,4-dibromobutanedione. Rabbit muscle pyruvate kinase is inactivated by both reagents in a biphasic manner with an initial rapid loss of 75% activity, followed by a slow total inactivation. The initial fast reaction with both compounds exhibits nonlinear dependence on reagent concentration, indicating formation of a reversible enzyme-reagent complex prior to covalent attachment. The presence of the gamma-phosphoryl group improves the performance of the affinity label: KI values for the fast phase are similar (about 100 microM), whereas kmax for 8-BDB-TATP is about three times greater than that of 8-BDB-TADP (0.286 min-1 vs 0.0835 min-1). After an 80-min incubation with 175 microM of either reagent, about 2 mol/mol of subunit is incorporated with 76% inactivation caused by 8-BDB-TADP and 97% inactivation by 8-BDB-TATP. Loss of activity is prevented by substrates, with the best protection afforded by a combination of ATP, Mn2+, K+, and phosphoenolpyruvate. Reaction of pyruvate kinase with either compound in the presence of protecting ligands leads to incorporation of about 1 mol of reagent/mol of subunit with only about 15% loss of activity. These results suggest that 8-BDB-TADP and 8-BDB-TATP react with two groups on the enzyme, one of which is at or near the active site.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induction and elimination of oscillations in continuous cultures of Saccharomyces cerevisiae

Continuous cultures of Saccharomyces cerevisiae are known to exhibit oscillatory behavior in the oxidative region. Important findings of a series of experiments conducted to identify the causes for initiation of and the means for elimination of oscillations in these cultures are reported in this paper. These oscillations are seen to be connected to the growth kinetics of the microorganism and are induced at very low glucose concentrations and at dissolved oxygen (DO) levels that are neither high nor low (DO values between 20 and 78% air saturation at a dilution rate of 0.2 h(-1) and pH of 5.5 at 30 degrees C). The oscillatory behavior is encountered over a range of dilution rates (0.09-0.25 h(-1) at 30 degrees C for pH = 5.5 and DO = 50% air saturation). The oscillations can be eliminated by raising the DO level above a critical value or by lowering the DO level below a critical value.