The role of cortical pattern in timing of cell division and morphogenesis in Stentor.

This paper describes experiments involving reciprocal exchange of the oral apparatus between a large (L) and a small (S) strain of Stentor coeruleus. Mature L-strain stentors given and S-strain oral apparatus formed an oral primordium in response to the presence of abnormally small oral structures and mostly divided although a few reorganized instead. Conversely, when S-strain stentors in early division were given a large L-strain oral apparatus, they resorbed the developing primordium and returned to interphase. When combined with previous results, these findings provide evidence for the hypothesis that the time of cell division in Stentor is determined by a "critical" ratio between the size of the oral apparatus and the size of the cell body (somatic) cortex. This ratio develops because the somatic cortex grows during interphase and the oral apparatus does not. Cell division in Stentor therefore appears to be initiated by a cortical pattern change resulting from cell surface growth during interphase.     

Potential use of a thermal water cyanobacterium as raw material to produce biodiesel and pigments

Bioprocess and Biosystems Engineering - Global energy demand is increasing every day and most is still derived from non-renewable sources. Therefore, sustainable alternatives are sought to produce...     

Root morphology,gas exchange and chlorophyll fluorescence of coffee cultivars and progenies are altered by Meloidogyne paranaensis infestation and water deficit

Climate change greatly influences coffee production, especially in areas infested with plant-parasitic nematodes. In this study, coffee genotypes showed differences in their morphological and physiological characteristics when subjected to a water deficit and parasitism by Meloidogyne paranaensis. The cultivar IPR 100 had the largest superficial and volumetric root system area, even when parasitized. The two progenies (MG 0179-1 and MG 0179-3) and the cultivar Catuaí IAC 62 had a similar surface area (p < .05) when parasitized. However, the root surface area and volume of MG 0179-3 increased by 96% and 400%, respectively, when parasitized by M. paranaensis. On the other hand, Catuaí IAC 62 had a 31% reduction in root surface area. Catuai 62 and IPR 100 showed higher sensitivity to drought when parasitized because of the increased photochemical sensitivity and reduction in photochemical quenching. In MG 0179-1 and MG 0179-3, an increase in non-photochemical quenching occurred in response to stress, indicating that these progenies use a photochemical response to protect photosystem II. In this work, MG 0179-3, which is resistant to M. paranaensis, was remarkable because, interestingly, the infestation caused an increase in its root surface area. In addition, MG 0179-3 had relatively good photochemical performance under water deficit and M. paranaensis parasitism.     

Induction of digestive alpha-amylases in larvae of Zabrotes subfasciatus (Coleoptera: Bruchidae) in response to ingestion of common bean alpha-amylase inhibitor 1

Zabrotes subfasciatus larvae possess three alpha-amylase isoforms determined by in gel assays following SDS-PAGE. Two minor isoforms present lower electrophoretic mobility than the major form. When developed inside Vigna unguiculata (cowpea) seeds, fourth instar larvae have minor quantities of the slow-migrating isoforms, but when reared on seeds of Phaseolus vulgaris (common bean), the two slow-migrating forms are expressed in higher amounts, whilst the quantity of the major constitutive form is independent of the host bean. Larvae at the beginning of the fourth instar were fed on flour or cotyledons of cowpea and common bean and it was observed that the larvae fed on the common bean expressed the two slow-migrating forms in higher amounts when compared to the control larvae fed on cowpea. In order to investigate the possible correlation between the induction of alpha-amylases and the ingestion of the common bean alpha-amylase inhibitor 1 (alphaAI-1), this inhibitor was incorporated into artificial diet. It was observed that larvae fed on diet containing chronic doses of alphaAI-1 during their development, produced the two slow-migrating forms in higher amounts than control larvae, however, fourth-instar larvae fed on the same diet presented less amylase activity than control larvae. The data suggested that alphaAI-1 is involved in amylase induction and that it has inhibitory activity against the constitutive amylase, when starch granules are used as substrate.     

Tryptophan hydroxylase is modulated by L-type calcium channels in the rat pineal gland

Calcium is an important second messenger in the rat pineal gland, as well as cAMP. They both contribute to melatonin synthesis mediated by the three main enzymes of the melatonin synthesis pathway: tryptophan hydroxylase, arylalkylamine N-acetyltransferase and hydroxyindole-O-methyltransferase. The cytosolic calcium is elevated in pinealocytes following alpha(1)-adrenergic stimulation, through IP(3)-and membrane calcium channels activation. Nifedipine, an L-type calcium channel blocker, reduces melatonin synthesis in rat pineal glands in vitro. With the purpose of investigating the mechanisms involved in melatonin synthesis regulation by the L-type calcium channel, we studied the effects of nifedipine on noradrenergic stimulated cultured rat pineal glands. Tryptophan hydroxylase, arylalkylamine N-acetyltransferase and hydroxyindole-O-methyltransferase activities were quantified by radiometric assays and 5-hydroxytryptophan, serotonin, N-acetylserotonin and melatonin contents were quantified by HPLC with electrochemical detection. The data showed that calcium influx blockaded by nifedipine caused a decrease in tryptophan hydroxylase activity, but did not change either arylalkylamine N-acetyltransferase or hydroxyindole-O-methyltransferase activities. Moreover, there was a reduction of 5-hydroxytryptophan, serotonin, N-acetylserotonin and melatonin intracellular content, as well as a reduction of serotonin and melatonin secretion. Thus, it seems that the calcium influx through L-type high voltage-activated calcium channels is essential for the full activation of tryptophan hydroxylase leading to melatonin synthesis in the pineal gland.     

To Investigate the Necessity of STRA6 Upregulation in T Cells during T Cell Immune Responses

Our earlier study revealed that STRA6 (stimulated by retinoic acid gene 6) was up-regulated within 3 h of TCR stimulation. STRA6 is the high-affinity receptor for plasma retinol-binding protein (RBP) and mediates cellular vitamin A uptake. We generated STRA6 knockout (KO) mice to assess whether such up-regulation was critical for T-cell activation, differentiation and function. STRA6 KO mice under vitamin A sufficient conditions were fertile without apparent anomalies upon visual inspection. The size, cellularity and lymphocyte subpopulations of STRA6 KO thymus and spleen were comparable to those of their wild type (WT) controls. KO and WT T cells were similar in terms of TCR-stimulated proliferation in vitro and homeostatic expansion in vivo. Naive KO CD4 cells differentiated in vitro into Th1, Th2, Th17 as well as regulatory T cells in an analogous manner as their WT counterparts. In vivo experiments revealed that anti-viral immune responses to lymphocytic choriomeningitis virus in KO mice were comparable to those of WT controls. We also demonstrated that STRA6 KO and WT mice had similar glucose tolerance. Total vitamin A levels are dramatically lower in the eyes of KO mice as compared to those of WT mice, but the levels in other organs were not significantly affected after STRA6 deletion under vitamin A sufficient conditions, indicating that the eye is the mouse organ most sensitive to the loss of STRA6.Our results demonstrate that 1) in vitamin A sufficiency, the deletion of STRA6 in T cells does no affect the T-cell immune responses so-far tested, including those depend on STAT5 signaling; 2) STRA6-independent vitamin A uptake compensated the lack of STRA6 in lymphoid organs under vitamin A sufficient conditions in mice; 3) STRA6 is critical for vitamin A uptake in the eyes even in vitamin A sufficiency.     

Effects of the blockade of high voltage-activated calcium channels on in vitro pineal melatonin synthesis

The presence of high voltage-activated calcium channels in the rat pineal gland is well known. However, their role in pineal metabolism is not completely understood and is even controversial. Better to understand this matter, we investigated the effects of L-, N- or P/Q-type calcium channel blockers (nifedipine, omega-conotoxin GVIA, omega-agatoxin IVA, respectively) on melatonin content and arylalkylamine-N-acetyltransferase activity of denervated rat pineal glands kept for 48 h in culture and stimulated with norepinephrine. Melatonin was measured by high performance liquid chromatography with electrochemical detection and arylalkylamine-N-acetyltransferase activity was quantified by radiometric assay. Pre-incubation with any of these high voltage-activated calcium channel blockers reduced the melatonin production induced by norepinephrine although arylalkylamine-N-acetyltransferase activity was reduced only by the N-type calcium channel antagonist, omega-conotoxin GVIA. The results indicate that calcium influx through L-, N- or P/Q-type of high voltage-activated calcium channels is necessary for the full expression of the metabolic process leading to melatonin synthesis in the rat pineal glands. However, the mechanisms involved in this process are different for the L- or P/Q- and N-type calcium channels.     

Evolutionary Significance of the Entepicondylar Foramen of the Humerus in New World Monkeys (Platyrrhini)

Although consistently absent in extant catarrhine monkeys, the presence and absence of the entepicondylar foramen of the humerus (EEF) vary greatly among living and fossil platyrrhines. Aiming to test the mode of evolution of this character in platyrrhine phylogeny, we performed stochastic character mapping of the presence and absence of the EEF based on museum material and literature research. We also tested for phylogenetic signal of the EEF and its correlation with semi-brachation, vertical clinging, and manipulative foraging in New World monkeys. We found more losses than gains of the EEF in the Haplorhini and Platyrrhini phylogenies. The EEF showed a strong phylogenetic signal congruent with a Brownian model of evolution. All models that assumed a dependence between foraging and locomotion behaviors showed a better fit to the data, but the differences from an independent model were not statistically significant. Thus, we assume that the observed pattern could have originated from genetic drift, except in Leontopithecus where the EEF appears to have been lost due to the narrowing of the distal humerus. Although not functionally relevant, the presence and absence of EEF is taxonomically useful for discriminating between the Aotus and Callicebus species groups, and diagnoses large platyrrhine clades such as marmosets and Atelidae. Thus, it should be considered when inferring systematic relationships among living and extinct platyrrhines.     

Phosphatidylinositol 3-Kinase/AKT Pathway Inhibition by Doxazosin Promotes Glioblastoma Cells Death,Upregulation of p53 and Triggers Low Neurotoxicity

Glioblastoma is the most frequent and malignant brain tumor. Treatment includes chemotherapy with temozolomide concomitant with surgical resection and/or irradiation. However, a number of cases are resistant to temozolomide, as well as the human glioblastoma cell line U138-MG. We investigated doxazosin’s (an antihypertensive drug) activity against glioblastoma cells (C6 and U138-MG) and its neurotoxicity on primary astrocytes and organoptypic hippocampal cultures. For this study, the following methods were used: citotoxicity assays, flow cytometry, western-blotting and confocal microscopy. We showed that doxazosin induces cell death on C6 and U138-MG cells. We observed that doxazosin’s effects on the PI3K/Akt pathway were similar as LY294002 (PI3K specific inhibitor). In glioblastoma cells treated with doxasozin, Akt levels were greatly reduced. Upon examination of activities of proteins downstream of Akt we observed upregulation of GSK-3β and p53. This led to cell proliferation inhibition, cell death induction via caspase-3 activation and cell cycle arrest at G0/G1 phase in glioblastoma cells. We used in this study Lapatinib, a tyrosine kinase inhibitor, as a comparison with doxazosin because they present similar chemical structure. We also tested the neurocitotoxicity of doxazosin in primary astrocytes and organotypic cultures and observed that doxazosin induced cell death on a small percentage of non-tumor cells. Aggressiveness of glioblastoma tumors and dismal prognosis require development of new treatment agents. This includes less toxic drugs, more selective towards tumor cells, causing less damage to the patient. Therefore, our results confirm the potential of doxazosin as an attractive therapeutic antiglioma agent.