The microbial degradation of morpholine

Morpholine can be completely degraded microbiologically, and two organisms have been isolated, each capable of growth in a simple mineral salts medium with morpholine as the sole source of carbon, nitrogen and energy. Excess nitrogen is liberated as ammonia. The enzymes responsible for the oxidation of morpholine are inducible and, in organism Mor G, will also oxidize piperidine, piperazine and pyrrolidine, which are not growth substrates. Ethanolamine is a likely intermediate, though the metabolic steps in morpholine degradation do not give rise solely to acetyl-CoA. After a period of acclimation, a laboratory scale activated sludge plant effectively removed morpholine over the long period it was operated; the sludge was also capable of nitrification. The possible effects of other chemicals in trade wastes containing morpholine on nitrification and morpholine oxidation are described.     

Discriminatory Role of Detergent-Resistant Membranes in the Dimerization and Endocytosis of Prostate-Specific Membrane Antigen

Prostate-specific membrane antigen (PSMA) is a type-II membrane glycoprotein that was initially identified in LNCaP cells. It is expressed at elevated levels in prostate cancer. In view of the correlation between the expression levels of PSMA and disease grade and stage, PSMA is considered to be one of the most promising biomarkers in the diagnosis and treatment of prostate cancer. In LNCaP cells PSMA undergoes internalization via clathrin-coated pits followed by accumulation in the endosomes. PSMA associates with different types of detergent-resistant membranes (DRMs) along the secretory pathway. Its mature form is mainly insoluble in Lubrol WX, but does not associate with Triton X-100-DRMs. To understand the mechanism of PSMA internalization we investigated its association during internalization with DRMs. For this purpose, internalization was induced by antibody cross-linking. We demonstrate at the biochemical and cell biological levels that: [i] exclusively homodimers of PSMA are associated with Lubrol WX-DRMs, [ii] antibody-induced cross-linking of PSMA molecules results in a time-dependent partitioning into another DRMs type, namely Triton X-100-DRMs, and [iii] concomitant with its association with Triton-X-100-DRMs internalization of PSMA occurs along tubulin filaments. In a previous work (Colombatti et al. (2009) PLoS One 4: e4608) we demonstrated that the small GTPases RAS and RAC1 and the MAPKs p38 and ERK1/2 are activated during antibody cross-linking. As downstream effects of this activation we observed a strong induction of NF-kB associated with an increased expression of IL-6 and CCL5 genes and that IL-6 and CCL5 enhanced the proliferative potential of LNCaP cells synergistically. These observations together with findings reported here hypothesize a fundamental role of DRMs during activation of PSMA as platforms for trafficking, endocytosis and signalling. Understanding these mechanisms constitutes an essential prerequisite for utilization of PSMA as a therapeutically suitable target in prostate cancer.     

Longitudinal Metabolomic Profiling of Amino Acids and Lipids across Healthy Pregnancy

Pregnancy is characterized by a complexity of metabolic processes that may impact fetal development and ultimately, infant health outcomes. However, our understanding of whole body maternal and fetal metabolism during this critical life stage remains incomplete. The objective of this study is to utilize metabolomics to profile longitudinal patterns of fasting maternal metabolites among a cohort of non-diabetic, healthy pregnant women in order to advance our understanding of changes in protein and lipid concentrations across gestation, the biochemical pathways by which they are metabolized and to describe variation in maternal metabolites between ethnic groups. Among 160 pregnant women, amino acids, tricarboxylic acid (TCA) cycle intermediates, keto-bodies and non-esterified fatty acids were detected by liquid chromatography coupled with mass spectrometry, while polar lipids were detected through flow-injected mass spectrometry. The maternal plasma concentration of several essential and non-essential amino acids, long-chain polyunsaturated fatty acids, free carnitine, acetylcarnitine, phosphatidylcholines and sphingomyelins significantly decreased across pregnancy. Concentrations of several TCA intermediates increase as pregnancy progresses, as well as the keto-body β-hydroxybutyrate. Ratios of specific acylcarnitines used as indicators of metabolic pathways suggest a decreased beta-oxidation rate and increased carnitine palmitoyltransferase-1 enzyme activity with advancing gestation. Decreasing amino acid concentrations likely reflects placental uptake and tissue biosynthesis. The absence of any increase in plasma non-esterified fatty acids is unexpected in the catabolic phase of later pregnancy and may reflect enhanced placental fatty acid uptake and utilization for fetal tissue growth. While it appears that energy production through the TCA cycle increases as pregnancy progresses, decreasing patterns of free carnitine and acetylcarnitine as well as increased carnitine palmitoyltransferase-1 rate and β-hydroxybutyrate levels suggest a concomitant upregulation of ketogenesis to ensure sufficient energy supply in the fasting state. Several differences in metabolomic profiles between Hispanic and non-Hispanic women demonstrate phenotypic variations in prenatal metabolism which should be considered in future studies.     

Stomatal and photosynthetic responses during sun/shade transitions in subalpine plants: influence on water use efficiency

Summary Different response patterns in net photosynthesis (A) leaf conductance (g) and water use efficiency (WUE= a/transpiration) in three subalpine plants occurred during experimental sun/shade transitions that simulated natural cloudcover. In Frasera speciosa Dougl., a large-leaved herb characteristic of open sites, g was relatively insensitive to transitions in irradiance and variations in A. However, large decreases in leaf temperature resulted in reduced transpiration during shade intervals and relatively constant WUE throughout the experimental sun/shade regime. In the understory herb, Arnica cordifolia Hook., patterns of A and g were similar during sun/shade transitions, but WUE was substantially reduced compared to steady-state levels. A third, somewhat intermediate pattern of A, g, and WUE was found in Artemisia tridentata L., an open site shrub. Higher intercellular CO₂ values in A. tridentata suggested that internal, cellular limitations to A were high relative to stomatal limitations in this shrub when compared to the herbaceous species.     

Nonparametric confidence interval estimators for heritability and expected selection response

Statistical methods have not been described for comparing estimates of family-mean heritability (H) or expected selection response (R), nor have consistently valid methods been described for estimating R intervals. Nonparametric methods, e.g., delete-one jackknifing, may be used to estimate variances, intervals, and hypothesis test statistics in estimation problems where parametric methods are unsuitable, nonrobust, or undefinable. Our objective was to evaluate normal-approximation jackknife interval estimators for H and R using Monte Carlo simulation. Simulations were done using normally distributed within-family effects and normally, uniformly, and exponentially distributed between-family effects. Realized coverage probabilities for jackknife interval (2) and parametric interval (5) for H were not significantly different from stated probabilities when between-family effects were normally distributed. Coverages for jackknife intervals (3) and (4) for R were not significantly different from stated coverages when between-family effects were normally distributed. Coverages for interval (3) for R were occasionally significantly less than stated when between-family effects were uniformly or exponentially distributed. Coverages for interval (2) for H were occasionally significantly less than stated when between-family effects were exponentially distributed. Thus, intervals (3) and (4) for R and (2) for H were robust. Means of analysis of variance estimates of R were often significantly less than parametric values when the number of families evaluated was 60 or less. Means of analysis of variance estimates of H were consistently significantly less than parametric values. Means of jackknife estimates of H calculated from log transformed point estimates and R calculated from untransformed or log transformed point estimates were not significantly different from parametric values. Thus, jackknife estimators of H and R were unbiased. Delete-one jackknifing is a robust, versatile, and effective statistical method when applied to estimation problems involving variance functions. Jackknifing is especially valuable in hypothesis test estimation problems where the objective is comparing estimates from different populations.     

Measurement of light within thin plant tissues with fiber optic microprobes

Vogelmann, T. C., Knapp, A. K., McClean, T. M. and Smith, W. K. 1988. Measurement of light within thin plant tissues with fiber optic microprobes. - Physiol. Plant. 72: 623–630.
The measurement of light with fiber optic microprobes has been extended to thin (200–300 μm) plant tissue samples. To test the method, light measurements were made in thin aqueous films and paradermal sections from 10-day-old etiolated Cucurbita pepo L. cv. Fordhook cotyledons. The measurements obtained were highly reproducible. Paradermal sections of spongy mesophyll that were irradiated with collimated light scattered light more effectively than the palisade layer of intact cotyledons. These results demonstrate that different plant tissues have different light scattering characteristics. The successful extension of the fiber optic microprobe technique to thin systems makes it possible to examine the optical properties of different cell layers within leaves and other plant organs.     

Regulation of the CD2 alternate pathway of T cell activation by CD3. Evidence for heterologous desensitization

Normal resting T cells were stimulated through the alternate CD2 pathway. A CD3 mAb VIT3 completely blocked their proliferative response. The time interval for 50% inhibition lasted for 24 h after the onset of CD2 stimulation. Mitogen-activated cloned long term cultured T cells could also be stimulated via CD2. This proliferative response was again inhibitable by VIT3, indicating that CD3 regulates the CD2 pathway not only in resting cells, but also in lymphocytes actively involved in an Ir. T cells were further loaded with Quin2 and their free cytoplasmic Ca2+ levels were monitored in response to CD3 and CD2 stimulation. Antibodies directed against both surface R triggered a rapid elevation of Ca2+ levels. Both responses were abrogated when the cells had been treated overnight with VIT3. The free cytoplasmic Ca2+ levels of VIT3-pretreated cells, however, were not higher than those of control cells. These results point to a functional interaction between CD3 and CD2 possibly at the level of signal transducing proteins. Finally, cholera toxin was found to inhibit the Ca2+ response in Jurkat T cells. Both the CD3 and CD2 stimulation were sensitive to cholera toxin, indicating that a GTP-binding protein may be involved in signal transduction for both surface structures.     

Antidepressants and seizure-interactions at the GABA-receptor chloride-ionophore complex

Convulsive seizures are a potential side effect of antidepressant drug treatment and can be produced by all classes of antidepressants. It is also known that some convulsant and anticonvulsant drug actions are mediated by the GABA-receptor chloride-ionophore complex. Drugs acting at this complex appear to induce convulsions by inhibiting chloride conductance through the associated chloride channel. Using the method of GABA-stimulated 36Cl-uptake by rat cerebral cortical vesicles, we show that some antidepressant drugs (imipramine, amitryptyline, and mianserine) can inhibit the GABA-receptor chloride uptake, and that the degree of chloride channel inhibition by these drugs correlates with the frequency of convulsive seizures induced by them.     

Endurance training in dogs increases vascular responsiveness to an alpha 1-agonist

The effects of endurance training on vascular responsiveness to an alpha 1-agonist and the associated changes in baroreflex modulation of heart rate and vascular resistance were studied. Graded dosages of phenylephrine were given to eight treadmill-trained dogs and to eight untrained dogs; both groups were chronically instrumented and were sedated and resting when tested. These dosages were repeated after ganglionic blockade. Aortic pressure, cardiac output, central venous pressure, peripheral resistance, and heart rate were each averaged over 30 s before injection and 90 s after injection. The slope of the peripheral resistance-dose relationship was significantly increased in trained compared with untrained dogs in both the unblocked and blocked cases [unblocked: trained 0.89, untrained 0.47; blocked: trained 4.30, untrained 2.05 (mmHg.l-1.min)/(microgram.kg-1)]. The unblocked resistance slopes were reduced with respect to the blocked slopes by 77 (untrained) and 79% (trained). The slope of the heart rate-aortic pressure response was reduced, but not significantly, by endurance training. We conclude that 6 wk of endurance training in dogs resulted in a doubling of the vascular responsiveness to an alpha 1-agonist, with no significant change in the baroreflex regulation of resistance or heart rate.