Toxoplasma gondii infection reduces predator aversion in rats through epigenetic modulation in the host medial amygdala

Male rats (Rattus novergicus) infected with protozoan Toxoplasma gondii relinquish their innate aversion to the cat odours. This behavioural change is postulated to increase transmission of the parasite to its definitive felid hosts. Here, we show that the Toxoplasma gondii infection institutes an epigenetic change in the DNA methylation of the arginine vasopressin promoter in the medial amygdala of male rats. Infected animals exhibit hypomethylation of arginine vasopressin promoter, leading to greater expression of this nonapeptide. The infection also results in the greater activation of the vasopressinergic neurons after exposure to the cat odour. Furthermore, we show that loss of fear in the infected animals can be rescued by the systemic hypermethylation and recapitulated by directed hypomethylation in the medial amygdala. These results demonstrate an epigenetic proximate mechanism underlying the extended phenotype in the Rattus novergicus–Toxoplasma gondii association.     

Pitfalls in compressed sensing reconstruction and how to avoid them

Multidimensional NMR can provide unmatched spectral resolution, which is crucial when dealing with samples of biological macromolecules. The resolution, however, comes at the high price of long experimental time. Non-uniform sampling (NUS) of the evolution time domain allows to suppress this limitation by sampling only a small fraction of the data, but requires sophisticated algorithms to reconstruct omitted data points. A significant group of such algorithms known as compressed sensing (CS) is based on the assumption of sparsity of a reconstructed spectrum. Several papers on the application of CS in multidimensional NMR have been published in the last years, and the developed methods have been implemented in most spectral processing software. However, the publications rarely show the cases when NUS reconstruction does not work perfectly or explain how to solve the problem. On the other hand, every-day users of NUS develop their rules-of-thumb, which help to set up the processing in an optimal way, but often without a deeper insight. In this paper, we discuss several sources of problems faced in CS reconstructions: low sampling level, missassumption of spectral sparsity, wrong stopping criterion and attempts to extrapolate the signal too much. As an appendix, we provide MATLAB codes of several CS algorithms used in NMR. We hope that this work will explain the mechanism of NUS reconstructions and help readers to set up acquisition and processing parameters. Also, we believe that it might be helpful for algorithm developers.     

In vivo ultraviolet-exposed human epidermal cells activate T suppressor cell pathways that involve CD4+CD45RA+ suppressor-inducer T cells

In vivo UV exposure of human epidermis abrogates the function of CD1+DR+ Langerhans cells and induces the appearance of CD1-DR+ Ag-presenting macrophages. Epidermal cells from UV-exposed skin, in contrast to epidermal cells from normal skin, potently activate autologous CD4+ T cells, and, in particular, the CD45RA+ (2H4+) (suppressor-inducer) subset. We therefore determined whether UV-exposure in humans leads to a T cell response in which suppression dominates. Autologous blood T cells were incubated with epidermal cell suspensions from in vivo UV-irradiated skin. After activation, repurified T cells were transferred in graded numbers to autologous mononuclear cells (MNC) stimulated with PWM and the resultant IgG production analyzed by ELISA. Relative to T cells activated by unirradiated control epidermal cells, T cells activated by UV-exposed epidermal cells demonstrated enhanced capacity to suppress IgG production (n = 6; p less than or equal to 0.03). Within the T cell population, CD8+ cells stimulated by UV-exposed epidermal cells could be directly activated to suppress PWM-stimulated MNC Ig production if IL-2 was provided in the reaction mixture. The suppressive activity was also transferable with purified CD4+ T cells stimulated by UV-exposed epidermal cells (n = 10; p less than or equal to 0.01), and was radiosensitive. Suppression was decreased when PWM-stimulated MNC were depleted of CD8+ T cells before mixing with CD4+ T cells activated by UV-exposed epidermal cells, suggesting indirect induction of CD8+ Ts cells contained within the responding MNC populations. Indeed, physical depletion of CD45RA+ cells resulted in total abrogation of the suppressor function contained in the CD4+ T cells. Activation of suppressor function was critically dependent on DR+ APC contained in UV-exposed epidermis. The data suggest that UV-exposure modulates cutaneous APC activity in humans, as in mice, such that the dominant immune response is tilted toward suppression. These mechanisms in normal individuals may function to dampen responses to UV-induced endogenous Ag that are pathogenic in autoimmune disorders. However, these mechanisms might also facilitate the growth of UV-induced skin cancers.     

Protease-mediated degradation of lignin peroxidase in liquid cultures of Phanerochaete chrysosporium

The decline of lignin peroxidase (LiP) activity observed after day 6 in cultures of Phanerochaete chrysosporium was found to be correlated with the appearance of idiophasic extracellular protease activity. Daily addition of glucose started on day 6 resulted in low protease levels and in turn in stable LiP levels. Addition of cycloheximide to day 6 cultures resulted in virtually no change of LiP activity and extracellular protein and negligible levels of protease activity, indicating that this protease is synthesized de novo. LiP activity was found to be stable upon removal of the fungal pellets on day 6 and incubation of the extracellular fluid alone. An almost complete disappearance of LiP activity and LiP proteins and high levels of protease activity were observed upon incubation of 6-day extracellular fluid in the presence of fungal pellets. Moreover, incubation of crude or purified LiP isoenzymes with protease-rich extracellular fluid of day 11 or 11-day cell extracts resulted in a marked loss of activity. In contrast, incubation of crude LiP with boiled and clarified extracellular fluid of day 11 cultures resulted in virtually no loss of activity. These results indicate that protease-mediated degradation of LiP proteins is a major cause for the decay of LiP activity during late secondary metabolism in cultures of P. chrysosporium.     

Breeding lines of the Indian mega-rice variety,MTU 1010, possessing protein kinase <Emphasis Type="Italic">OsPSTOL</Emphasis> (<Emphasis Type="Italic">Pup1</Emphasis>), show better root system architecture and higher yield in soils with low phosphorus

MTU 1010 is a high-yielding mega-variety of rice grown extensively in India. However, it does not perform well in soils with low phosphorus (P) levels. With an objective to improve MTU 1010 for tolerance to low soil P, we have transferred Pup1, a major quantitative trait locus (QTL) associated with tolerance from another mega-variety, Swarna, through marker-assisted backcross breeding (MABB). Foreground selection of the F₁ and backcross plants was performed with the co-dominant, closely linked CAPS marker, K20-2, while two flanking markers RM28011 and RM28157 were utilized for recombinant selection. At each backcross generation, positive plants were also analyzed with a set of 85 parental polymorphic SSR markers to identify the QTL-positive plants possessing maximum introgression of MTU 1010 genome. At BC₂F₁, the best backcross plant was selfed to generate BC₂F₂s. Among them, the plants homozygous for Pup1 (n?=?22) were reconfirmed using the functional marker for Pup1, viz., K46-1, and they were advanced through pedigree method of selection until BC₂F₆ generation. A total of five elite BC₂F₆ lines, possessing Pup1 and phenotypically similar to MTU 1010, were screened in the low soil P plot and normal plot (with optimum soil P levels) during wet season, 2016. All the selected lines showed better performance under low P soil with more number of productive tillers, better root system architecture, and significantly higher yield (>?390%) as compared to MTU 1010. Further, under normal soil, the lines were observed to be similar to or better than MTU 1010 for most of the agro-morphological traits and yield. This study represents the successful application of marker-assisted selection for improvement of tolerance to low soil P in a high-yielding Indian rice variety.     

Identification of dynorphin 1-8 in human placenta by mass spectrometry

The human placental villus tissue contains opioid receptors and peptides. The opioid peptides extracted from the villus tissue were fractionated using reverse-phase high performance liquid chromatography and a radio-receptor assay. The presence of dynorphin 1-8 was corroborated by mass spectrometric production of (M + H) ion in the fast atom bombardment mode. This octa-peptide could be the natural ligand of the kappa opioid receptors present in the human placental villus tissue.     

Glutamine as a gamma-glutamyl donor for gamma-glutamyl transpeptidase: gamma-glutamyl peptide formation

This study demonstrates the formation of gamma-glutamyl peptides from glutamine and plasma amino acids, as catalyzed by gamma-glutamyl transpeptidase. It also establishes the effect of various amino acids in modulating the rate of glutamine utilization as well as the hydrolytic or transfer product formed. The mechanism of the utilization of glutamine as catalyzed by gamma-glutamyl transpeptidase, involves the formation of a gamma-glutamyl enzyme bound intermediate as the initial step, with release of the amide nitrogen as ammonium, NH+4, Figure 1. The gamma-glutamyl enzyme bound intermediate either reacts with the acceptor amino acids or water; reaction with amino acids yields gamma-glutamylpeptides via the transfer pathway and reaction with water yields glutamate via the hydrolytic pathway.     

Evidence for lumenal and antilumenal localization of gamma-glutamyltranspeptidase in rat kidney

Gamma-Glutamyl-p-nitroanilide (γ-GpNA) utilization was studied using the isolated rat kidney perfused with 1.5 mM γ-glutamyl-p-nitroanilide and 8 mM glycylglycine (glygly). In the absence of glygly, autotransfer products, γ-glu-γ-glu-p-NA appeared in the perfusate while glutamate, the hydrolytic product, appeats in the urine. In the presence of glygly, p-nitroaniline (p-NA) formation was stimulated 3-fold with the appearance of γ-gluglygly as the major product in both the perfusate and urine. Under conditions of single pass perfusion, 89 percent of the γ-glutamyl-p-nitroanilide utilization occurs on the antilumenal border and only 11 percent on the lumenal border; ureter ligation reduced glomerular filtration 90 percent but does not significantly reduce utilization. However, reducing the perfusate flow rate of the antilumenal side to that of the lumenal results in a utilization rate which is approximately one-third that of the lumenal, suggesting that the lumenal border enzyme is at least 3 times in excess of the antilumenal border enzyme.     

Examination of Droughtmaster bulls for breeding soundness

Forty Droughtmaster bulls were evaluated for breeding soundness, using the method of examination and criteria for classifying bulls of the Society for Theriogenelogy. Eighty three percent of the bulls were classified as satisfactory, 14 percent as questionable and 3 percent as unsatisfactory breeders. Scrotal circumference for 2 to 8-year-old bulls were smaller in questionable and unsatisfactory bulls, as compared to satisfactory bulls. For bulls rated as satisfactory breeders, the scrotal circumference of 37 to 43 cms was higher than for other beef breeds. Three related bulls (2 questionable, 1 satisfactory) carried sperm defects classified as 'knobbed' (38 +/- 3%), 'Dag' (40 +/- 4%) and 'pseudo-droplets' (41 +/- 5%), which may adversely affect fertility.