Ultrastructural Analysis of the Sensilla of Austroperipatus aequabilis Reid, 1996 (Onychophora,Peripatopsidae)

The head of Austroperipatus aequabilis bears five types of sensilla. which were examined by electron microscopy. They differ from each other in position, shape of outer sensory elements and cuticular socket structures. Thus, we distinguish sensilla with sensory hairs, sensilla with sensory bulbs, cone-shaped sensilla. sensilla with sensory bristles, and sensilla of the lips. They are composed of up to 15 cells, which can he separated into four cell types. The most frequent cell type is the bipolar receptor cell that occurs in all sensilla. The apical surface of this primary receptor cell is characterized by one or two partly branched cilia with a basal 9 × 2 + 0 pattern of microtubules. A modified bipolar receptor cell was found in all sensilla bearing a sensory peg except for the sensilla equipped with sensory bristles. The apical dendrite extends to a long pale process which exclusively contains mitochondria and single microtubules. In all sensilla examined in this study at least one supporting cell occurs which is characterized by parallel microvilli. An additional function of this cell type as a part of the stimulus-conducting system is possible. In the sensillum with a sensory bulb two kinds of supporting cells occur. A unique cell type with an upside down position has regularly been found in all sensilla bearing a sensory peg. Apart from the sensilla they also occur within the labial epidermis. Since most sensilla contain several different receptor cells, they can be considered as complex sense organs. © 1998 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd. All rights reserved     

Sperm velocity in an Alpine whitefish: effects of age, size, condition, fluctuating asymmetry and gonad abnormalities

The relationship between sperm velocity and individual age, size, body condition and fluctuating asymmetry was investigated in Alpine whitefish Coregonus fatioi . The fish analysed belonged to one among several sympatric whitefish populations of Lake Thun, Switzerland, which are characterized by a high prevalence of gonad alterations. Therefore, sperm velocity data were also tested for a link between gonad deformation and sperm swimming speed. Sperm velocity was significantly lower in larger-grown individuals and in individuals of higher body condition. As expected, sperm velocity was higher in males with higher levels of fluctuating asymmetry, but it did not significantly vary with male age. Moreover, variation in sperm velocity was found to be significantly higher in individuals showing some types of gonad alterations but it did not significantly correlate with the presence of other types of alterations.     

Glucocorticoids synergize with IL-1β to induce TLR2 expression via MAP Kinase Phosphatase-1-dependent dual Inhibition of MAPK JNK and p38 in epithelial cells

Background  

Despite the importance of glucocorticoids in suppressing immune and inflammatory responses, their role in enhancing host immune and defense response against invading bacteria is poorly understood. Toll-like receptor 2 (TLR2) has recently gained importance as one of the major host defense receptors. The increased expression of TLR2 in response to bacteria-induced cytokines has been thought to be crucial for the accelerated immune response and resensitization of epithelial cells to invading pathogens.     

Strong feature sets from small samples.

For small samples, classifier design algorithms typically suffer from overfitting. Given a set of features, a classifier must be designed and its error estimated. For small samples, an error estimator may be unbiased but, owing to a large variance, often give very optimistic estimates. This paper proposes mitigating the small-sample problem by designing classifiers from a probability distribution resulting from spreading the mass of the sample points to make classification more difficult, while maintaining sample geometry. The algorithm is parameterized by the variance of the spreading distribution. By increasing the spread, the algorithm finds gene sets whose classification accuracy remains strong relative to greater spreading of the sample. The error gives a measure of the strength of the feature set as a function of the spread. The algorithm yields feature sets that can distinguish the two classes, not only for the sample data, but for distributions spread beyond the sample data. For linear classifiers, the topic of the present paper, the classifiers are derived analytically from the model, thereby providing an enormous savings in computation time. The algorithm is applied to cancer classification via cDNA microarrays. In particular, the genes BRCA1 and BRCA2 are associated with a hereditary disposition to breast cancer, and the algorithm is used to find gene sets whose expressions can be used to classify BRCA1 and BRCA2 tumors.     

Intervention in context-sensitive probabilistic Boolean networks

MOTIVATION: Intervention in a gene regulatory network is used to help it avoid undesirable states, such as those associated with a disease. Several types of intervention have been studied in the framework of a probabilistic Boolean network (PBN), which is essentially a finite collection of Boolean networks in which at any discrete time point the gene state vector transitions according to the rules of one of the constituent networks. For an instantaneously random PBN, the governing Boolean network is randomly chosen at each time point. For a context-sensitive PBN, the governing Boolean network remains fixed for an interval of time until a binary random variable determines a switch. The theory of automatic control has been previously applied to find optimal strategies for manipulating external (control) variables that affect the transition probabilities of an instantaneously random PBN to desirably affect its dynamic evolution over a finite time horizon. This paper extends the methods of external control to context-sensitive PBNs. RESULTS: This paper treats intervention via external control variables in context-sensitive PBNs by extending the results for instantaneously random PBNs in several directions. First, and most importantly, whereas an instantaneously random PBN yields a Markov chain whose state space is composed of gene vectors, each state of the Markov chain corresponding to a context-sensitive PBN is composed of a pair, the current gene vector occupied by the network and the current constituent Boolean network. Second, the analysis is applied to PBNs with perturbation, meaning that random gene perturbation is permitted at each instant with some probability. Third, the (mathematical) influence of genes within the network is used to choose the particular gene with which to intervene. Lastly, PBNs are designed from data using a recently proposed inference procedure that takes steady-state considerations into account. The results are applied to a context-sensitive PBN derived from gene-expression data collected in a study of metastatic melanoma, the intent being to devise a control strategy that reduces the WNT5A gene's action in affecting biological regulation, since the available data suggest that disruption of this influence could reduce the chance of a melanoma metastasizing.     

The non-homologous end-joining pathway is not involved in the radiosensitization of mammalian cells by heat shock

A synergistic increase in cell killing is observed when a heat-shock is administered prior to, during, or immediately after exposure to ionizing radiation (IR). This phenomenon, known as heat-radiosensitization, is believed to be mediated by inhibition of repair of radiation-induced double strand breaks (DSB) when cells are exposed to temperatures above 42 degrees C. However, the mechanism by which heat inhibits DSB repair is unclear. The bulk of radiation-induced DSBs are repaired via the non-homologous end-joining pathway (NHEJ). Several reports indicate that the Ku70 and Ku80 subunits of the mammalian DNA-dependent protein kinase (DNA-PK), a complex involved in NHEJ, appear to be susceptible to a heat-induced loss of DNA-binding activity, with Ku80 representing the heat-sensitive component. Since the heat-induced loss and subsequent recovery of Ku-DNA binding activity correlates well with heat-radiosensitization, a role for Ku80 and NHEJ in heat-radiosensitization has been proposed. However, direct evidence implicating Ku80 (and NHEJ) in heat-radiosensitization has been indeterminate. In this study, we demonstrate that equitoxic heat treatments at 42.5-45.5 degrees C induce a similar amount of aggregation of Ku80 in human U-1 melanoma cells. These data suggest that the time-temperature-dependent relationship between heat lethality and Ku80 aggregation are similar. However, the aggregation/disaggregation of Ku80 and its transient or permanent inactivation is unrelated to heat-radiosensitization. When survival curves were obtained for irradiated or irradiated and heated Ku80(-/-) mouse embryo fibroblasts (MEFs) and compared with survival curves obtained for wild-type (WT) cells, we found that heat-radiosensitization was not reduced in the Ku80(-/-) cells, but actually increased. Thus, our findings indicate that Ku80 is not essential for heat-radiosensitization. Non-involvement of Ku-dependent or Ku-independent NHEJ pathways in heat-radiosensitization was confirmed by comparing clonogenic survival between DNA ligase IV-defective and WT human cells. Our data therefore implicate homologous recombination in inhibition of repair of radiation-induced DSBs and as a target for heat-radiosensitization.     

Effects of some dietary phytoestrogens in animal studies: review of a confusing landscape

A variety of effects have been attributed to phytoestrogens, which are present in variable concentrations in soy-based laboratory animal diets. The authors review the inherent complexities in evaluating the effects of soy and dietary phytoestrogens on various in vitro and in vivo systems.     

Molecular dynamics and IR spectroscopy in investigation of phase transitions in molecular crystal 4,4'-bis(11-hydroxy-1-undecyloxy)biphenyl

Molecular dynamics (MD) simulations combined with temperature-dependent IR spectroscopic measurements were used to study phase transitions in molecular crystals of the mesogenic diol 4,4'-bis(11-hydroxy-1-undecyloxy)biphenyl. DSC measurements revealed four phase transitions in this molecular crystal at approximately 327.1 K, 389.8 K, 419.1 K and 431.9 K. Analysis of the dynamic trajectories at temperatures of 300 K, 360 K, 400 K and 480 K revealed changes in conformation of the mesogenic diol molecules and consequently changes in crystal packing and crystal structure in the temperature range 300-480 K and enabled us to understand the mechanism of the phase transitions.