Tubulin glycylases are required for primary cilia,control of cell proliferation and tumor development in colon

TTLL3 and TTLL8 are tubulin glycine ligases catalyzing posttranslational glycylation of microtubules. We show here for the first time that these enzymes are required for robust formation of primary cilia. We further discover the existence of primary cilia in colon and demonstrate that TTLL3 is the only glycylase in this organ. As a consequence, colon epithelium shows a reduced number of primary cilia accompanied by an increased rate of cell division in TTLL3-knockout mice. Strikingly, higher proliferation is compensated by faster tissue turnover in normal colon. In a mouse model for tumorigenesis, lack of TTLL3 strongly promotes tumor development. We further demonstrate that decreased levels of TTLL3 expression are linked to the development of human colorectal carcinomas. Thus, we have uncovered a novel role for tubulin glycylation in primary cilia maintenance, which controls cell proliferation of colon epithelial cells and plays an essential role in colon cancer development.     

Infection by trypanosomes in marsupials and rodents associated with human dwellings in Ecuador

Small mammals trapped in domestic and peridomestic environments of rural Ecuador were screened for trypanosome infection by direct microscopy and hemoculture. Identification of species of trypanosomes was then performed by morphological characteristics and by polymerase chain reaction (PCR) assays. Of 194 animals collected, 15 were positive for infection (7.73%). Eight (4.12%) were infected with Trypanosoma cruzi (1 of 33 Didelphis marsupialis; 7 of 61 Rattus rattus). Eleven R. rattus (18.03%) harbored T. lewisi, 5 of which presented mixed infections with T. cruzi. Additionally, 1 of 3 Oryzomys xanthaeolus was infected with T. rangeli. No trypanosome infection was detected in Philander opossum (n = 1), Mus musculus (n = 79), Rattus norvegicus (n = 8), Akodon orophilus (n = 4), Sigmodon peruanus (n = 3), or Proechimys decumanus (n = 2). Many of the isolates belong to T. cruzi, the causative agent of Chagas disease, and R. rattus had the highest prevalence. Because of its abundance in the study areas, this species is considered an important reservoir for Chagas disease. This is the first report of T. lewisi and T. rangeli in Ecuador. This study is also the first to describe natural mixed infections of T. cruzi-T. lewisi.     

HistoChoice® as an alternative to formalin fixation of undecalcified bone specimens

We compared histochemical and immunohistochemical staining as well as fluorochrome labeling in murine bone specimens that were fixed with 10% neutral buffered formalin to those fixed with HistoChoice®. We showed that sections from undecalcified tibiae fixed for 4 h in HistoChoice® resulted in enhanced toluidine blue and Von Kossa histochemical staining compared to formalin fixation. HistoChoice® produced comparable or improved staining for alkaline phosphatase. Acid phosphatase localization was better in formalin fixed specimens, but osteoclasts were visuralized more easily in HistoChoice® fixed specimens. As expected, immunohistochemical labeling was antibody dependent; some antibodies labeled better in HistoChoice® fixed specimens while others were better in formalin fixed specimens. Toluidine blue, Von Kossa, and alkaline phosphatase staining of sections fixed for 12 h produced sections that were similar to 4 h fixed sections. Fixation for 12 h preserved acid phosphatase activity better. Increasing fixation to 12 h affected immunolocalization differentially. Bone sialoprotein labeling in HistoChoice® fixed specimens was comparable to formalin fixed samples. On the other hand, after 12 h formalin fixation, osteocalcin labeling was comparable to HistoChoice®. For most histochemical applications, fixing murine bone specimens for 4 h with HistoChoice® yielded superior staining compared to formalin fixation. If immunohistochemical localization is desired, however, individual antibodies must be tested to determine which fixation process retains antigenicity better. In addition, there was no detectable difference in the intensity of fluorochrome labeling using either fixative. Finally, fixation duration did not alter the intensity of labeling.     

Deficit irrigation for enhancing sustainable water use: Comparison of cotton nitrogen uptake and prediction of lint yield in a multivariate autoregressive state-space model

Deficit irrigation is an optimization strategy for achieving sustainability of irrigated crop production. A field-study of cotton (Gossypium hirsutum L.) response to a limited water supply was conducted in an Alfisol in the southern High Plains of Texas. The objectives were to investigate cotton N uptake, canopy temperature, plant spectral index and lint yield variation under deficit irrigation and to provide information for enhancing sustainability of the water resources and Alfisols in the semi-arid environment. The experimental treatments were two deficit-irrigation levels at 50% and 75% of cotton evapotranspiration (ET). Plant and soil variables were measured 15 m apart along the center-pivot irrigation circles. The results show that cotton plants under the 50%-ET deficit irrigation level were 21% more water stressed (P < 0.05) based on the reflectance water index ratio. The 50%-ET irrigation resulted in a 25% lint yield loss with a 33% water saving compared to the higher irrigation level (75%-ET). Plant reflectance, canopy temperature, total N uptake and lint yield were correlated with normalized difference vegetative index (NDVI), soil water content (SWC), soil NO₃-N concentrations and elevation (−0.69 < r < 0.72, P < 0.05, respectively). Future cotton lint yield is weighted on NDVI and water variation, quantified in a multivariate autoregressive state-space model. Increases in plant reflectance in the water band are signs of early plant water stress. Compared to the 12-year regional cotton lint yield obtained with full irrigation, the 75%-ET deficit irrigation would be agronomical, economical efficient in Alfisoils with only 7.8% of lint-yield loss from water stress but 25% of water saving for sustainable water use.     

Expression of the MDR-1 gene-encoded P-glycoprotein in cardiomyocytes of conscious sheep undergoing acute myocardial ischemia followed by reperfusion.

We have recently reported that in chronic myocardial ischemia, adult mammalian cardiomyocytes express P-glycoprotein (P-gp). We now investigate if P-gp is also expressed in acute regional ischemia followed by reperfusion. Adult conscious sheep underwent 12-min occlusion of the mid-left anterior descending artery (inflatable cuff). Successful ischemia-reperfusion was confirmed by monitoring percent systolic left ventricular anterior wall thickening (sonomicrometry) during the whole ischemic period and every 10 min over 2 hr following cuff deflation. At 3, 24, and 48 hr after reperfusion, P-gp expression was investigated by immunohistochemistry and Western blot and MDR-1 mRNA by RT-PCR. Cardiomyocytes in the occluded artery territory (but not those in remote areas) consistently expressed P-gp at their sarcolemma. Whereas at 3 and 24 hr P-gp was mainly observed in the T tubules, at 48 hr it predominated in intercalated discs and gap junctions. RT-PCR and Western blot revealed higher expression in ischemic than in control myocardium. We conclude that in adult sheep with acute myocardial ischemia, the MDR-1 gene-encoded P-gp is expressed at the sarcolemma of the cardiomyocytes from 3 hr up to at least 48 hr after reperfusion.     

Household risk factors for Trypanosoma cruzi seropositivity in two geographic regions of Ecuador

Few studies on the relationship between environmental factors and Trypanosoma cruzi transmission have been conducted in Ecuador. We conducted a cross-sectional study of household risk factors for T. cruzi seropositivity in 2 distinct geographical regions of Ecuador. Exposure information was collected via household surveys, and subjects were tested for serological evidence of T. cruzi infection. In total, 3,286 subjects from 997 households were included. In the coastal region, factors associated with seropositivity were living in a house with a palm roof (odds ratio [OR] = 2.63, 95% confidence interval, [1.61. 4.27]), wood walls (OR = 5.75 [2.04, 16.18]), or cane walls (OR = 2.81 11.31, 6.04]), and the presence of firewood in the peridomicile (OR = 2.48 [1.54, 4.01]). Accumulation of trash outside the home was associated with a reduced risk of seropositivity (OR = 0.25 [0.12, 0.51]). In the Andean region, living in a house with adobe walls was the only factor predictive of T. cruzi seropositivity. In conclusion, risk factors for T. cruzi transmission in Ecuador varied by geographic region, probably because of differing behavior of the triatomine vector species in each region. An understanding of the transmission dynamics of T. cruzi in a particular area is necessary for the development of effective Chagas disease control strategies in those areas.     

TAP score: torsion angle propensity normalization applied to local protein structure evaluation

Background  

Experimentally determined protein structures may contain errors and require validation. Conformational criteria based on the Ramachandran plot are mainly used to distinguish bet ween distorted and adequately refined models. While the readily available criteria are sufficient to detect totally wrong structures, establishing the more subtle differences between plausible structures remains more challenging.