The Thatcher illusion in humans and monkeys

Primates possess the remarkable ability to differentiate faces of group members and to extract relevant information about the individual directly from the face. Recognition of conspecific faces is achieved by means of holistic processing, i.e. the processing of the face as an unparsed, perceptual whole, rather than as the collection of independent features (part-based processing). The most striking example of holistic processing is the Thatcher illusion. Local changes in facial features are hardly noticeable when the whole face is inverted (rotated 180°), but strikingly grotesque when the face is upright. This effect can be explained by a lack of processing capabilities for locally rotated facial features when the face is turned upside down. Recently, a Thatcher illusion was described in the macaque monkey analogous to that known from human investigations. Using a habituation paradigm combined with eye tracking, we address the critical follow-up questions raised in the aforementioned study to show the Thatcher illusion as a function of the observer''s species (humans and macaques), the stimulus'' species (humans and macaques) and the level of perceptual expertise (novice, expert).     

Interaction of fatigue and hypercapnia in the canine diaphragm

We studied 10 open-chest dogs and measured the pressure across the diaphragm (Pdi) in each period of the protocol during stimulation at frequencies of 1, 20, 50, and 80 Hz. Three ranges of arterial PCO2 (PaCO2) were examined: less than or equal to 26, 36-50, and greater than or equal to 89 Torr. The diaphragm was fatigued with repetitive phrenic stimulation (30 Hz). During the fatiguing activity, five of the animals were subjected to hypercapnia and the other five to hypocapnia. A frequency-Pdi curve was generated for each period in the protocol. The data show that 1) fatiguing to 50% of the initial Pdi value during hypercapnia was significantly more rapid than during hypocapnia; 2) both the prefatigue and postfatigue mean Pdi values over all interactions of frequency, fatigue, and PaCO2 were unaffected by the fatiguing environment (hypercapnia vs. hypocapnia); 3) the percent reduction of Pdi by hypercapnia was the same at all four frequencies; 4) hypocapnia did not alter either the pre- or postfatigue frequency-Pdi curve; and 5) one-half relaxation time, unaffected by PaCO2, was prolonged by fatigue. We conclude that the hypercapnic diaphragm has less endurance than the hypocapnic diaphragm and that although both fatigue and hypercapnia decrease Pdi, they appear to be separate entities working through different mechanisms.     

Production of pectinases by Aspergillus niger in solid state fermentation at high initial glucose concentrations

Exopectinase (exo-p) and endopectinase (endo-p) production by Aspergillus niger CH4 in solid state culture was studied at initial glucose concentrations of 100, 250, 350 and 450 g/l. The highest activity of exo-p (35 U/g) was produced at 72 and 120 h in the medium containing 100 and 250 g glucose/l, respectively. The maximum endo-p activity (9 U/g) was produced at 72 h in the medium with 250 g glucose/l. The reduction in pectinase production at 350 and 450 g/l initial glucose concentration was due neither to repression of the synthesis of the enzyme nor to the glucose consumption rate of the strain but due to a drastic drop in pH of the medium.S. Solis-Pereyra, E. Favela-Torres, M. Gutiérrez-Rojas, G. Saucedo-Castañeda and G. Viniegra-González are with the Departamento de Biotecnologia, Universidad Autónoma Metropolitana, A.P. 55-535, C.P. 09340, México D.F., México; S. Roussos is with the Laboratoire de Biotechnologie, ORSTOM, B.P. 5045, 34032, Montpellier Cedex, France, and P. Gunasekaran is with the Department of Microbial Technology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625-021, India.     

Secondary structure of mouse and rabbit α- and β-globin mRNAs: Differential accessibility of α and β initiator AUG codons towards nucleases

The nucleotide sequence from the 5′ terminus inward of one third of mouse α- and β^maj-globin messenger RNAs has been established. In addition, using 5′ ³²P end-labeled mRNAs as substrates and S1 and T1 nucleases as probes for single-stranded regions, the secondary structures of mouse and rabbit α- and β-globin mRNAs have been analyzed. Our results indicate that the AUG initiator codon in both mouse and rabbit β-globin mRNA is quite susceptible to cleavage with S1 and T1 nucleases, suggesting that it resides in a single-stranded exposed region. In contrast, the initiator AUG in the α-globin mRNA of both species is inaccessible to cleavage, indicating that it is either buried by tertiary structure or is base-paired. Since the rate of initiation of protein synthesis with β-globin mRNA in rabbit reticulocyte is 30–40% faster than for α-globin mRNA, these results imply a possible correlation between the differential rates of initiation with these two mRNAs and the accessibility of the respective AUG initiator codons.     

Strategies for large scale inoculum development for solid state fermentation system: Conidiospores of Trichoderma harzianum

Summary The suitability of disc fermenter for efficient production of conidiospores by Trichoderma harzianum is limited to a working capacity of 0.61 agar medium due to large decrease in spore production per cm² of the culture surface area with further increase in the capacity. In contrast, Zymotis, a large scale solid state fermenter designed at ORSTOM, France and use of inert solid support for absorbing nutrients offer many advantages for production of conidiospores in quantity sufficient enough to inoculate pilot and larger fermenters. Five times higher production of conidiospores in Zymotis, as compared to the agar medium in flask, constitutes a success in the development of large scale inoculum.     

Effects of diaphragmatic ischemia on the inspiratory motor drive.

To assess the effect of diaphragmatic ischemia on the inspiratory motor drive, we studied the in situ isolated and innervated left diaphragm in anesthetized, vagotomized, and mechanically ventilated dogs. The arterial and venous vessels of the left diaphragm were catheterized and isolated from the systemic circulation. Inspiratory muscle activation was assessed by recording the integrated electromyographic (EMG) activity of the left and right costal diaphragms and parasternal intercostal and alae nasi muscles. Tension generated by the left diaphragm during spontaneous breathing attempts was also measured. In eight animals, left diaphragmatic ischemia was induced by occluding the phrenic artery for 20 min, followed by 10 min of reperfusion. This elicited a progressive increase in EMG activity of the left and right diaphragms and parasternal and alae nasi muscles to 170, 157, 152, and 128% of baseline values, respectively, an increase in the frequency of breathing efforts, and no change in left diaphragmatic spontaneous tension. Thus the ratio of left diaphragmatic EMG to tension rose progressively during ischemia. During reperfusion, only the frequency of breathing efforts and alae nasi EMG recovered completely. In four additional animals, left diaphragmatic ischemia was induced after the left phrenic nerve was sectioned. Neither EMG activity of inspiratory muscles nor respiratory timing changed significantly during ischemia. In conclusion, diaphragmatic ischemia increases inspiratory motor drive through activation of phrenic afferents. The changes in alae nasi activity and respiratory timing indicate that this influence is achieved through supraspinal pathways.     

Effect of phrenic afferent stimulation on pattern of respiratory muscle activation.

Ventilation and electromyogram (EMG) activities of the right hemidiaphragm, parasternal intercostal, triangularis sterni, transversus abdominis, genioglossus, and alae nasi muscles were measured before and during central stimulation of the left thoracic phrenic nerve in 10 alpha-chloralose anesthetized vagotomized dogs. Pressure in the carotid sinuses was fixed to maintain baroreflex activity constant. The nerve was stimulated for 1 min with a frequency of 40 Hz and stimulus duration of 1 ms at voltages of 5, 10, 20, and 30 times twitch threshold (TT). At five times TT, no change in ventilation or EMG activity occurred. At 10 times TT, neither tidal volume nor breathing frequency increased sufficiently to reach statistical significance, although the change in their product (minute ventilation) was significant (P less than 0.05). At 20 and 30 times TT, increases in both breathing frequency and tidal volume were significant. At these stimulus intensities, the increases in ventilation were accompanied by approximately equal increases in the activity of the diaphragm, parasternal, and alae nasi muscles. The increase in genioglossus activity was much greater than that of the other inspiratory muscles. Phrenic nerve stimulation also elicited inhomogeneous activation of the expiratory muscles. The transversus abdominis activity increased significantly at intensities from 10 to 30 times TT, whereas the activity of the triangularis sterni remained unchanged. The high stimulation intensities required suggest that the activation of afferent fiber groups III and IV is involved in the response. We conclude that thin-fiber phrenic afferent activation exerts a nonuniform effect on the upper airway, rib cage, and abdominal muscles and may play a role in the control of respiratory muscle recruitment.     

EGFR and HER2 exert distinct roles on colon cancer cell functional properties and expression of matrix macromolecules

Background

ErbB receptors, EGFR and HER2, have been implicated in the development and progression of colon cancer. Several intracellular pathways are mediated upon activation of EGFR and/or HER2 by EGF. However, there are limited data regarding the EGF-mediated signaling affecting functional cell properties and the expression of extracellular matrix macromolecules implicated in cancer progression.

Methods

Functional assays, such as cell proliferation, transwell invasion assay and migration were performed to evaluate the impact of EGFR/HER2 in constitutive and EGF-treated Caco-2 cells. Signaling pathways were evaluated using specific intracellular inhibitors. Western blot was also utilized to examine the phosphorylation levels of ERK1/2. Real time PCR was performed to evaluate gene expression of matrix macromolecules.

Results

EGF increases cell proliferation, invasion and migration and importantly, EGF mediates overexpression of EGFR and downregulation of HER2. The EGF–EGFR axis is the main pathway affecting colon cancer's invasive potential, proliferative and migratory ability. Intracellular pathways (PI3K-Akt, MEK1/2-Erk and JAK-STAT) are all implicated in the migratory profile. Notably, MT1- and MT2-MMP as well as TIMP-2 are downregulated, whereas uPA is upregulated via an EGF–EGFR network. The EGF–EGFR axis is also implicated in the expression of syndecan-4 and TIMP-1. However, glypican-1 upregulation by EGF is mainly mediated via HER2.

Conclusions and general significance

The obtained data highlight the crucial importance of EGF on the expression of both receptors and on the EGF–EGFR/HER2 signaling network, reveal the distinct roles of EGFR and HER2 on expression of matrix macromolecules and open a new area in designing novel agents in targeting colon cancer. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.     

In vitro propagation of olive (Olea europaea L.) cv. Koroneiki

Single node explants of 'Koroneiki' olive trees werecultured for one month on a modified Driver-Kuniyuki for Walnut medium, lackinggrowth regulators. The explants were subcultured once a month on a mediumsupplemented with zeatin riboside, 6-(--dimethylallylamino)purine,6-benzyladenine or thidiazuron. Zeatin riboside proved to be superior to othercytokinins in inducing shoot proliferation. The combination of olive knotextract at 25 or 50 mg l^–1 with cytokininssuppressed shoot proliferation. After two months at the proliferation stage,theexplants were cultured for one week in the dark in 1 ml liquidWoody Plant Medium supplemented with IBA, -NAA or IBA+-NAA. Theexplants were then transferred to the same solid medium lacking growthregulators, with a small layer of perlite on the surface. The combination ofthetwo auxins at 1+1 mg l^–1 resulted in almost 76%rooting. The combination of olive knot extract at 50 mgl^–1 with auxins increased the rooting percentage up toalmost 87%. Artificial infection of explants with the bacteriumPseudomonas savastanoi pv. savastanoiinhibited rhizogenesis, even in the presence of auxins. Rooted explants weresuccessfully acclimatised under a mist system, with the survival rate reachingalmost 75%.