Triacylglycerols are synthesised and utilized by transacylation reactions in microsomal preparations of developing safflower (Carthamus tinctorius L.) seeds

Microsomal membrane preparations from the immature cotyledons of safflower (Carthamus tinctorius) catalysed the interconversion of the neutral lipids, mono-, di-, and triacylglycerol. Membranes were incubated with neutral lipid substrates, ¹⁴C-labelled either in the acyl or glycerol moiety, and the incorporation of radioactivity into other complex lipids determined. It was clear that diacylglycerol gave rise to triacylglycerol and monoacylglycerol as well as phosphatidylcholine. Radioactivity from added [¹⁴C] triacylglycerol was to a small extent transferred to diacylglycerol whereas added [¹⁴C] monoacylglycerol was rapidly converted to diacylglycerols and triacylglycerols. The formation of triacylglycerol from diacylglycerol occurred in the absence of acyl-CoA and hence did not involve diacylglycerol acyltransferase (DAGAT) activity. Monoacylglycerol was not esterified by direct acylation from acyl-CoA. We propose that these reactions were catalyzed by a diacylglycerol: diacylglycerol transacylase which yielded triacylglycerol and monoacylglycerol, the reaction being freely reversible. The specific activity of the transacylase was some 25% of the diacylglycerol acyltransferase activity and, hence, during the net accumulation of oil, substantial newly formed triacylglycerol equilibrated with the diacylglycerol pool. In its turn the diacylglycerol rapidly interconverted with phosphatidylcholine, the major complex lipid substrate for Δ12 desaturation. Hence, the oleate from triacylglycerols entering phosphatidylcholine via this route could be further desaturated to linoleate. A model is presented which reconciles these observations with our current understanding of fatty acid desaturation in phosphatidylcholine and oil assembly in oleaceous seeds. Received: 8 November 1996 / Accepted: 5 February 1997     

Low heritability in morphological characters of Tengmalm's owls: The role of cyclic food and laying date?

Summary In parent—offspring regressions, high heritability estimates of characters may simply be due to common environment: the resemblance between the living conditions of parents and their offspring in species showing restricted natal dispersal. In vole-eating Tengmalm's owls (Aegolius funereus), the natal dispersal and breeding dispersal of adult females are wide (up to > 1000 km and > 500 km, respectively), whereas adult males are resident. We found that body measurements of 183 recruits born in western Finland were independent of parental age and vole abundance in the birth year. Early-laid eggs produced longer winged recruits than late-laid eggs. The wing lengths of the daughters showed a significant positive regression on the wing length of their mothers, but the removal of the maternal effect via laying date lowered this relationship. The development time of offspring to the first autumn might also be crucial for morphological characters of females in their later life. Significant regressions were not found between the wing length of the son and his father. The mother—daughter regression was small for laying date, but positive (p = 0.08) for clutch size. These results suggest low heritability in breeding and morphological characters of owls and this low heritability may enable plastic adjustment to optimize fitness at any stage in a fluctuating environment. Nonadditive genetic variance also creates variation between offspring characters that are not genetically correlated with the parents and may explain these low heritability estimates.     

Effects of different cultivation temperatures on plasma membrane ATPase activity and lipid composition of sugar beet roots.

Sugar beet seedlings (Beta vulgaris L. cv. Monohill) were cultivated for 3 weeks at different root and shoot temperatures and the plasma membranes (PM) from roots were purified by aqueous two-phase partitioning and analyzed for lipid composition and ATPase activities. Lipid analyses, undertaken immediately after PM purification from the roots, showed that a low root zone temperature (10 degrees C) decreased the ratio between the major lipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE). A low temperature in the root environment increased the mol% of PE and decreased the mol% of phosphatidic acid (PA), independent on the shoot growth temperature. A low temperature also decreased the mol% of linoleic acid (18:2) and increased mol% of linolenic acid (18:3) in the analyzed lipid classes, especially in PC and PE. The ratio between acyl chain lipids and protein generally increased in PM from roots grown at 10 degrees C, compared with higher temperature. The changes in lipid composition correlated with changes in ATPase activities, detected as hydrolyses of MgATP. The kinetic parameters, K(m) and V of the PM H(+)ATPase in roots increased at a low cultivation temperature, independent on shoot temperature. Moreover, Arrhenius analyses showed that the transition temperature was independent of both root or shoot growth temperature at 10-24 degrees C, whereas the activation energy of the ATPase was dependent on the growth temperature of the root, and independent on shoot temperature. Thus, acclimation processes can take place in roots, irrespective of the shoot temperature.     

Gastric bypass surgery reveals independency of obesity and diabetes melitus type 2

Background

Roux-en-Y gastric bypass surgery is widely applied to ameliorate morbid obesity, including diabetes in people with type 2 diabetes. The latter vanish a few days after surgery for many, but not in all patients before any weight reduction has occurred. The explanation for this change in metabolic status is poorly understood, but the observation may suggest that the fate obesity and diabetes is only partly linked after surgery.

Methods

The trajectories of weight reduction measured as reduced body mass index (BMI) in 741obese subjects with and without diabetes were evaluated. Evaluation was performed on three groups: 1) subjects that were non-diabetic before and after surgery; 2) subjects that were diabetics before surgery but non-diabetics after surgery; and 3) subjects that were diabetics before surgery and remained diabetics after surgery. The diabetic state was established at HbA1c above 48 mmol/mol.

Results

The trajectories differ significantly between groups and any sub-populations of groups, the latter identified by the distance between individual trajectories using a k-means procedure. The results suggest that different domains in the enormous genetic network governing basic metabolism are perturbed in obesity and diabetes, and in fact some of the patients are affected by two distinct diseases: obesity and diabetes mellitus type 2.

Conclusion

Although RYGB “normalized” many glycaemic parameters in some of the diabetic subjects apparently converting to a non-diabetics state, other diabetic subjects stay diabetic in the context of the new gut anatomy after surgery. Thus, the obesity part of the glycaemic derangement may have been ameliorated, but some defects of the diabetic state had not.

     

Improving the Prediction of Prostate Cancer Overall Survival by Supplementing Readily Available Clinical Data with Gene Expression Levels of IGFBP3 and F3 in Formalin-Fixed Paraffin Embedded Core Needle Biopsy Material

Background

A previously reported expression signature of three genes (IGFBP3, F3 and VGLL3) was shown to have potential prognostic value in estimating overall and cancer-specific survivals at diagnosis of prostate cancer in a pilot cohort study using freshly frozen Fine Needle Aspiration (FNA) samples.

Methods

We carried out a new cohort study with 241 prostate cancer patients diagnosed from 2004–2007 with a follow-up exceeding 6 years in order to verify the prognostic value of gene expression signature in formalin fixed paraffin embedded (FFPE) prostate core needle biopsy tissue samples. The cohort consisted of four patient groups with different survival times and death causes. A four multiplex one-step RT-qPCR test kit, designed and optimized for measuring the expression signature in FFPE core needle biopsy samples, was used. In archive FFPE biopsy samples the expression differences of two genes (IGFBP3 and F3) were measured. The survival time predictions using the current clinical parameters only, such as age at diagnosis, Gleason score, PSA value and tumor stage, and clinical parameters supplemented with the expression levels of IGFBP3 and F3, were compared.

Results

When combined with currently used clinical parameters, the gene expression levels of IGFBP3 and F3 are improving the prediction of survival time as compared to using clinical parameters alone.

Conclusion

The assessment of IGFBP3 and F3 gene expression levels in FFPE prostate cancer tissue would provide an improved survival prediction for prostate cancer patients at the time of diagnosis.     

Subtypes of Hepatitis B Antigen in Blood Donors and Post-transfusion Hepatitis: Clinical and Epidemiological Aspects

Subtyping of hepatitis B antigen (HBA) in blood donors revealed subtype ad in 56% while patients with icteric post-transfusion hepatitis from the same centre showed subtype ay in the majority of the cases (75%). Donors with subtype ad in serum were mostly asymptomatic long-term carriers of the antigen with normal liver function (83%), while 70% of donors with subtype ay in serum had signs of acute or chronic liver disease. Healthy long-term carriers of HBA seem to present little risk of transmitting hepatitis irrespective of subtype. It is, however, possible that these differences in blood donors with subtype ad and patients with post-transfusion hepatitis with subtype ay might reflect epidemiological circumstances rather than biological differences in the two viral strains.     

DNA repair replication,DNA breaks and sister-chromatid exchange in human cells treated with adriamycin in vitro

The effects of adriamycin (AM) on DNA repair replication, the frequency of sister-chromatid exchange (SCE), the rate of cell proliferation and the frequency of DNA strand breaks were studied in human cells in vitro. No repair replication was observed in lymphocytes exposed to AM in concentrations up to 10^?3 moles/1. DNA repair replication induced by UV and alkylating agents was not affected by a concentration of AM that completely inhibited cell proliferation (10^?6 moles/1).Fibroblasts exposed to AM at 10^?4 moles/1 in the presence of hydroxyurea showed an increase of strand breaks and cross-links in DNA. When AM was added to UV-irradiated fibroblasts, there was an increase of DNA strand breaks in addition to the breaks caused by UV alone. Similar effects were observed in lymphocytes.A dose-dependent increase of SCE was observed in lymphocytes exposed to low concentrations of AM (<10^?7 moles/1). At higher concentrations the increase of SCE levelled off, and cell proliferation became severely inhibited. There was no evidence of removal of SCE-inducing damage in cells exposed to AM during G₀ or G₁. The level of SCE induced in the third cell cycle after treatment with AM was not different from that induced during the first two cell cycles.These results suggest that the various genotoxic and cytotoxic effects of AM are caused by different types of cellular damage. Moreover, AM-induced DNA damage persists for several cell cycles in human cells in vitro and seems to be resistant to repair activity.     

The distribution of the NADPH regenerating mannitol cycle among fungal species

The mannitol cycle is an important NADPH regenerating system in Alternaria alternata. The cycle is built up of the following enzymes: mannitol 1-phosphate dehydrogenase, mannitol 1-phosphatase, mannitol dehydrogenase and hexokinase. The net reaction of one cycle turn is: NADH+NADP⁺+ATP NAD⁺+NADPH+ADP+P_i. The enzymes needed for an operating cycle were found in Aspergillus, Botrytis, Penicillium, Pyricularia, Trichothecium, Cladosporium and Thermomyces all genera belonging to Fungi Imperfecti. The only genus of this class lacking the cycle was Candida. No genera from the classes Basidiomycetes and Phycomycetes showed any mannitol 1-phosphate dehydrogenase or mannitol 1-phosphatase activities. The genera investigated, belonging to Ascomycetes, Gibberella, Ceratocystis and Neurospora all lacked mannitol 1-phosphate dehydrogenase. It was concluded that the mannitol cycle is an important and widespread pathway for NADH oxidation and NADP⁺ reduction in the organisms belonging to the class Fungi Imperfecti.     

Menadione-induced cytotoxicity is associated with protein thiol oxidation and alteration in intracellular Ca2+ homeostasis

The toxicological implications of alterations in intracellular thiol homeostasis during menadione metabolism have been investigated using freshly isolated rat hepatocytes. A strict correlation between depletion of protein sulfhydryl groups and loss of cell viability was observed. Loss of protein thiols preceded cell death, and occurred more rapidly in cells with decreased levels of reduced glutathione. Depletion of protein thiols was also associated with inhibition of Ca²⁺ efflux from the cells and perturbation of intracellular Ca²⁺ homeostasis. It is proposed that the oxidative stress induced by menadione metabolism in isolated hepatocytes results in the depletion of both soluble and protein thiols, and that the latter effect is critically associated with a perturbation of Ca²⁺ homeostasis and loss of cell viability.