Characterisation of<Emphasis Type="Italic">fusarium graminearum</Emphasis> and<Emphasis Type="Italic">F. culmorum</Emphasis> isolates by mycotoxin production and aggressiveness to wheat

A total of 27Fusarium culmorum isolates from Germany and 41F. graminearum isolates from Kenya were investigated for aggressiveness and mycotoxin production on wheat ears. In addition, ergosterol content of the kernels from ears inoculated withF. graminearum was determined and theF. culmorum isolates were tested for mycotoxin productionin vitro. For both pathogens, isolates markedly differed in aggressiveness. 59% and 37% of theF. culmorum isolates produced NIV and DON, respectively,in vivo andin vitro. The DON-producing isolates also produced 3-acDONin vitro. The more aggressive isolates produced mainly DON while the less aggressive isolates produced mainly NIV. 12% and 85% of theF. graminearum isolates produced NIV and DON, respectively. The highly aggressive isolates produced higher amounts of DON, aggressiveness being highly correlated to DON content in the kernels. NIV-producing isolates were less aggressive. Ergosterol content of kernels was moderately correlated to aggressiveness but highly correlated to DON content. Disease severity was associated with kernel weight reduction.     

Thymosin Beta 4 and Thymosin Beta 10 Expression in Hepatocellular Carcinoma

Thymosin beta 4 (Tβ4) and thymosin beta 10 (Tβ10) are two members of the beta-thymosin family involved in many cellular processes such as cellular motility, angiogenesis, inflammation, cell survival and wound healing. Recently, a role for beta-thymosins has been proposed in the process of carcinogenesis as both peptides were detected in several types of cancer. The aim of the present study was to investigate the expression pattern of Tβ4 and Tβ10 in hepatocellular carcinoma (HCC). To this end, the expression pattern of both peptides was analyzed in liver samples obtained from 23 subjects diagnosed with HCC. Routinely formalin-fixed and paraffin-embedded liver samples were immunostained by indirect immunohistochemistry with polyclonal antibodies to Tβ4 and Tβ10. Immunoreactivity for Tβ4 and Tβ10 was detected in the liver parenchyma of the surrounding tumor area. Both peptides showed an increase in granular reactivity from the periportal to the periterminal hepatocytes. Regarding HCC, Tβ4 reactivity was detected in 7/23 cases (30%) and Tβ10 reactivity in 22/23 (96%) cases analyzed, adding HCC to human cancers that express these beta-thymosins. Intriguing finding was seen looking at the reactivity of both peptides in tumor cells infiltrating the surrounding liver. Where Tβ10 showed a strong homogeneous expression, was Tβ4 completely absent in cells undergoing stromal invasion.The current study shows expression of both beta-thymosins in HCC with marked differences in their degree of expression and frequency of immunoreactivity. The higher incidence of Tβ10 expression and its higher reactivity in tumor cells involved in stromal invasion indicate a possible major role for Tβ10 in HCC progression.Key words: β-thymosins, Tβ4, Tβ10, hepatocellular carcinoma, stromal invasion     

Artemis and Nonhomologous End Joining-Independent Influence of DNA-Dependent Protein Kinase Catalytic Subunit on Chromosome Stability

Deficiency in both ATM and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is synthetically lethal in developing mouse embryos. Using mice that phenocopy diverse aspects of Atm deficiency, we have analyzed the genetic requirements for embryonic lethality in the absence of functional DNA-PKcs. Similar to the loss of ATM, hypomorphic mutations of Mre11 (Mre11^ATLD1) led to synthetic lethality when juxtaposed with DNA-PKcs deficiency (Prkdc^scid). In contrast, the more moderate DNA double-strand break response defects associated with the Nbs1^ΔB allele permitted viability of some Nbs1^ΔB/ΔB Prkdc^scid/scid embryos. Cell cultures from Nbs1^ΔB/ΔB Prkdc^scid/scid embryos displayed severe defects, including premature senescence, mitotic aberrations, sensitivity to ionizing radiation, altered checkpoint responses, and increased chromosome instability. The known functions of DNA-PKcs in the regulation of Artemis nuclease activity or nonhomologous end joining-mediated repair do not appear to underlie the severe genetic interaction. Our results reveal a role for DNA-PKcs in the maintenance of S/G₂-phase chromosome stability and in the induction of cell cycle checkpoint responses.The Mre11 complex, consisting of Mre11, Rad50, and Nbs1 (Xrs2 in Saccharomyces cerevisiae), is involved in diverse aspects of DNA double-strand break (DSB) metabolism. The Mre11 complex acts as a DSB sensor, mediates cell cycle checkpoint arrest and apoptosis, and promotes DSB repair (47, 48). The influence of the Mre11 complex on DSB responses is attributable partly to its influence on ataxia-telangiectasia mutated (ATM) kinase activity (29). ATM is a central signal transducer in the response to DSBs and is required for arrest throughout the cell cycle, as well as the efficient execution of apoptosis in response to many types of genotoxic stress (43).The Mre11 complex is required for ATM activation and governs the phosphorylation of ATM substrates such as SMC1, Chk2, and BID (4, 6, 26, 47, 49, 51). The C terminus of Nbs1 interacts with ATM and plays an important role in facilitating a subset of these events, particularly those important for apoptosis (11, 14, 47, 58). However, ATM makes multiple functional contacts with members of the Mre11 complex. Nbs1, Mre11, and Rad50 are all ATM substrates, and many aspects of ATM checkpoint signaling are impaired by hypomorphic Mre11 and Nbs1 mutations that do not affect the ATM binding domain in the C terminus of Nbs1 (32, 36, 52, 54).Several molecular and genetic observations support the view that the Mre11 complex''s role in preserving genome stability is particularly relevant to the S and G₂ phases of the cell cycle (3, 56). The complex, predominantly nucleoplasmic in G₁ cells, becomes predominantly chromatin associated and colocalizes with PCNA throughout S phase (35, 38). This association is a likely prerequisite for the complex''s influence on DNA damage signaling as well as DNA repair.Cell cultures established with samples from patients with Nijmegen breakage syndrome (NBS1 hypomorphism) and ataxia-telangiectasia-like disorder (MRE11 hypomorphism) exhibit checkpoint defects in S phase and at the G₂/M transition, while the G₁/S transition is relatively unaffected. These checkpoint defects are correlated with reduced Mre11 complex chromatin association both in human cells and in mouse models of Nijmegen breakage syndrome and ataxia-telangiectasia-like disorder (5, 45, 49, 52). Chromosomal aberrations arising in these cells are predominantly chromatid type breaks, consistent with impaired metabolism of DNA replication-associated DNA breaks (49, 52).Further supporting a predominant role for the Mre11 complex in S phase is the observation that its primary role in DSB repair is the promotion of recombination between sister chromatids (3, 24). Structural and genetic evidence that the Mre11 complex effects molecular bridging between DNA duplexes offers a mechanistic basis for this observation (10, 23, 53). Molecular bridging by the Mre11 complex may also contribute to its influence on nonhomologous end joining (NHEJ) (12, 34, 57). Collectively, these data strongly support the view that the Mre11 complex''s checkpoint and DSB repair functions are manifested predominantly in the S and G₂ phases of the cell cycle.Although the Mre11 complex and ATM function in the same arm of the DNA damage response, ATM deficiency is lethal in hypomorphic Mre11 and Nbs1 mutants (Mre11^ATLD1/ATLD1 and Nbs1^ΔB/ΔB mice, respectively) (49, 52), suggesting that aspects of ATM function are Mre11 complex independent. ATM deficiency is also synthetically lethal with mutations in Prkdc, the gene encoding the catalytic subunit of the DNA-dependent protein kinase (DNA-PKcs) that is mutated in mice with severe combined immunodeficiency (Prkdc^scid mice) (22, 42). DNA-PKcs is an ATM paralog required for NHEJ, which appears to be the predominant mode of DSB repair in G₁ cells (16).Defective NHEJ is unlikely to be the basis for the embryonic lethality of Prkdc^−/− Atm^−/− or Prkdc^scid/scid Atm^−/− mice, as loss of ATM rescues the late embryonic lethality of both DNA ligase IV (Lig4) and XRCC4 null embryos, which have more severe NHEJ defects than Prkdc^scid mice abolished by the Atm^−/− genotype (31, 42). These observations argue that the DNA-PKcs functions required for viability in the absence of ATM do not include NHEJ.To address this issue, we crossed Mre11^ATLD1/ATLD1 and Nbs1^ΔB/ΔB mice with Prkdc^scid/scid mice. As these Mre11 complex hypomorphs do not completely phenocopy ATM deficiency, we reasoned that double-mutant animals would be viable and thus provide a venue in which to examine the functional relationship between the Mre11 complex/ATM arm of the DNA damage response and DNA-PKcs. Whereas the Mre11^ATLD1/ATLD1 mutation was synthetically lethal with the Prkdc^scid/scid genotype, some Nbs1^ΔB/ΔB Prkdc^scid/scid mice were born, consistent with the more moderate DNA damage response defects associated with the Nbs1^ΔB allele than with the Mre11^ATLD1 allele (48). Nbs1^ΔB/ΔB Prkdc^scid/scid embryos were born at drastically reduced Mendelian ratios, displayed gross developmental defects, and were severely runted. Nbs1^ΔB/ΔB Prkdc^scid/scid cell cultures exhibited profound chromosome instability, growth defects, and increased sensitivity to ionizing radiation (IR). DNA repair defects associated with DNA-PKcs deficiency did not appear to underlie the observed phenotypic synergy. Rather, the data suggest a novel regulatory function of DNA-PKcs in the maintenance of chromosomal stability during the S and G₂ phases of the cell cycle.     

Infestation of leek by Thrips tabaci as related to spatial and temporal patterns of undersowing

Full field undersowing of leeks with clovers suppresses populations of adult and larval Thrips tabaci. To explore the conditions for application of this approach of IPM in commercial practice, variations in the spatial and temporal pattern of clover undersowing were studied. Effects on thrips populations, crop growth and the development of thrips feeding symptoms were recorded. Assessment of the yield in quantity and quality was made. Sowing clover (Trifolium fragiferum) between rows resulted in significant and sufficient thrips population suppression and good yields. Similar results were achieved by full field sowing of clover simultaneous with leek crop planting. Reduced thrips feeding symptoms were found in intercropped leeks.     

Temporal encoding in nervous systems: A rigorous definition

We propose a rigorous definition for the termtemporal encoding as it is applied to schemes for the representation of information withinpatterns of neuronal action potentials, and distinguish temporal encoding schemes from those based on window-averagedmean rate encoding. The definition relies on the identification of anencoding time window, defined as the duration of a neuron's spike train assumed to correspond to a single symbol in the neural code. The duration of the encoding time window is dictated by the time scale of the information being encoded. We distinguish between the concepts of theencoding time window and theintegration time window, the latter of which is defined as the duration of a stimulus signal that affects the response of the neuron. We note that the duration of the encoding and integration windows might be significantly different. We also present objective, experimentally assessable criteria for identifying neurons and neuronal ensembles that utilize temporal encoding to any significant extent. The definitions and criteria are made rigorous within the contexts of several commonly used analytical approaches, including thestimulus reconstruction analysis technique. Several examples are presented to illustrate the distinctions between and relative capabilities of rate encoding and temporal encoding schemes. We also distinguish our usage oftemporal encoding from the termtemporal coding, which is commonly used in reference to the representation of information about thetiming of events by rate encoding schemes.     

Biomarkers of the one‐carbon pathway in association with congenital diaphragmatic hernia

Homocysteine is an intermediate of the one‐carbon (1‐C) pathway and increased concentrations have been related to neural crest‐related congenital anomalies. The neural crest and the 1‐C pathway might be involved also in the etiology of Congenital Diaphragmatic Hernia (CDH). In 22 CDH and 28 control newborns and their mothers, general characteristics were obtained by standardized questionnaires. The 1‐C pathway intermediates total homocysteine (tHcy), S‐adenosylmethionine (SAM), and S‐adenosylhomocysteine (SAH) were determined in cord blood. Correlations between maternal and newborn factors and risk estimates were investigated by univariate and multivariable logistic regression analyses. Birth weight (2962 vs. 3418 gram; p < 0.001) was lower and gestational age (270 vs. 277 days; p = 0.006) was shorter in case children. Control mothers were slightly older (32 vs. 35 year; p = 0.05). Other characteristics were comparable between case and control children and mothers. The concentrations of homocysteine, SAM and SAH, and the SAM/SAH ratio were comparable (tHcy: 8.57 vs. 8.56 μmol/l, p = 0.99; SAM: 152.7 vs. 157.3 nmol/l, p = 0.76; SAH: 43.5 vs. 48.9, p = 0.26; ratio: 3.8 vs. 3.5, p = 0.50). Maternal and newborn characteristics were not correlated to the biomarker concentrations. In conclusion, the biomarkers of methylation determined in cord blood are not associated with CDH risk. Maternal and child characteristics could not predict newborn biomarker concentrations of the 1‐C pathway. Birth Defects Research (Part A) 2012. © 2012 Wiley Periodicals, Inc.