The control of root, vegetative shoot and flower morphogenesis in tobacco thin cell-layer explants (TCLs)

Thin cell-layer explants (TCLs) have been proposed as favorable tissues for the study of root, vegetative shoot and flower formation. We tested the effects of pH, light quality, light quantity, and IBA and kinetin concentrations on the morphogenesis of TCLs cultured individually on a liquid medium. Alterations of the amounts of exogenously supplied IBA and kinetin were sufficient to induce the formation of roots, vegetative shoots and flowers on TCLs cultured on otherwise identical media. The type and number of organs formed were sensitive to the intensity of light (55, 75, 100 and 120 muEinsteins m-2 sec-1) under which TCLs were grown. Evidence was obtained that the effects of light on TCL morphogenesis were associated with photochemical degradation of IBA in the medium. Evaluation of the organogenesis that occurred in TCLs cultured on a medium containing a range of IBA and kinetin concentrations showed that the number and type of organs formed, and overall growth, were dependent upon the initial concentrations of auxin and cytokinin. We have developed the TCL culture system into a sensitive and reproducible bioassay for the study of morphogenesis. The advantages of using the TCL morphogenesis bioassay for the identification and study of molecules (e.g. cell wall oligosaccharides) that may regulate morphogenesis are discussed.     

The relationships between fish size and otolith dimensions in the common sole (Solea solea (Linnaeus, 1758)) captured in the Northeastern Mediterranean

Fish specimens were captured by a commercial bottom trawler at a depth of 50–80 m from Iskenderun Bay (Hatay, Turkey) between December 2017 and May 2018. The bottom trawl gear used was equipped with a 44 mm stretched mesh size net at the cod-end. Blind side and eyed side otolith lengths (OL), otolith breadths (OB) and otolith weights (OW) were measured from each specimen to the nearest 0.001 mm and 0.0001g respectively. A total of 110 fish (43 females and 67 males) were collected. Total length ranged from 20.8 to 28.2 cm and 68.0 to 166.1 g (males) and 21.1 to −28.5 cm and 74.5 to 201.4 g (females). The coefficients of determination between fish weight and otolith weight, and total length and otolith weight (sexes combined) were found as R² = .7694 (0.77) and R² = .6274 (0.63), respectively. A moderate positive relationship between the total length-otolith dimensions, and fish weight-otolith dimensions, was also demonstrated.     

Whole-Exome Sequencing Identifies Mutated C12orf57 in Recessive Corpus Callosum Hypoplasia

The corpus callosum is the principal cerebral commissure connecting the right and left hemispheres. The development of the corpus callosum is under tight genetic control, as demonstrated by abnormalities in its development in more than 1,000 genetic syndromes. We recruited more than 25 families in which members affected with corpus callosum hypoplasia (CCH) lacked syndromic features and had consanguineous parents, suggesting recessive causes. Exome sequence analysis identified C12orf57 mutations at the initiator methionine codon in four different families. C12orf57 is ubiquitously expressed and encodes a poorly annotated 126 amino acid protein of unknown function. This protein is without significant paralogs but has been tightly conserved across evolution. Our data suggest that this conserved gene is required for development of the human corpus callosum.     

Levels of superoxide dismutase and malondialdehyde in primary spontaneous pneumothorax

The aim of the present study is to determine whether patients with primary spontaneous pneumothorax (PSP) are subject to oxidative stress. For this purpose, we measured the activities of red blood cell superoxide dismutase, which is an antioxidant enzyme, and the level of plasma malondialdehyde, which is one of the lipid peroxidation markers, in a group of patients with PSP. The study was carried out with 16 patients with PSP and 24 healthy individuals. The two groups were similar to each other in terms of sex, age and smoking attitudes. Erythrocyte superoxide dismutase activity was found to be significantly lower in patients with PSP than in the control group (p < 0.01). The plasma malondialdehyde levels were significantly high in patients with PSP (p < 0.01). Our results suggest that oxidative stress may contribute to the pathogenesis of PSP.     

ATP activates ataxia-telangiectasia mutated (ATM) in vitro. Importance of autophosphorylation

Ataxia-telangiectasia Mutated (ATM), mutated in the human disorder ataxia-telangiectasia, is rapidly activated by DNA double strand breaks. The mechanism of activation remains unresolved, and it is uncertain whether autophosphorylation contributes to activation. We describe an in vitro immunoprecipitation system demonstrating activation of ATM kinase from unirradiated extracts by preincubation with ATP. Activation is both time- and ATP concentration-dependent, other nucleotides fail to activate ATM, and DNA is not required. ATP activation is specific for ATM since it is not observed with kinase-dead ATM, it requires Mn2+, and it is inhibited by wortmannin. Exposure of activated ATM to phosphatase abrogates activity, and repeat cycles of ATP and phosphatase treatment reveal a requirement for autophosphorylation in the activation process. Phosphopeptide mapping revealed similarities between the patterns of autophosphorylation for irradiated and ATP-treated ATM. Caffeine inhibited ATM kinase activity for substrates but did not interfere with ATM autophosphorylation. ATP failed to activate either A-T and rad3-related protein (ATR) or DNA-dependent protein kinase under these conditions, supporting the specificity for ATM. These data demonstrate that ATP can specifically induce activation of ATM by a mechanism involving autophosphorylation. The relationship of this activation to DNA damage activation remains unclear but represents a useful model for understanding in vivo activation.     

Endemic goiter, thiocyanate overload, and selenium status in school-age children

Iodine deficiency (ID) and related disorders are still major, yet unresolved health concerns. Recently, in a systematic survey of schoolage children (SAC), we reported severe to moderate ID, in Ankara and three cities from Black Sea region of Turkey. The current study attempted to evaluate selenium (Se) status, thiocyanate (SCN⁻) overload, and their possible contribution to the goiter endemics and thyroid hormone profile observed in these cities. Thyroid ultrasonography was performed and serum Se, SCN⁻, thyroid hormones, sensitive TSH (sTSH) levels, and urinary iodine concentrations (UICs) were determined from 251 SAC (9–11 yr old). Thyroid volumes (TVs) exceeding recommended upper normal limits and median UIC indicated goitre endemics and moderate to severe ID in the areas studied. Mean serum SCN⁻ concentrations were found to be greater than the controls from the literature. The UIC/SCN⁻ ratio was found to be lowest in Bayburt and Trabzon denoting that SCN⁻ overload may contribute to the goiter endemics. Serum Se concentrations represent a marginal deficiency in the four areas studied. No significant correlations between serum Se concentrations and the other parameters studied (i.e., TV, SCN⁻, thyroid hormones, sTSH, UIC) was detected. In conclusion, this study showed that selenium is also marginally deficient in the iodine-deficient endemic areas studied, but this has little or no impact on the thyroid hormone profile and the goiter endemics. SCN⁻ overload may contribute to the endemics, especially for the areas where iodine is severely deficient. An effective iodine supplementation program will not only resolve the goiter endemics but also the consequence of SCN⁻ overload as well in the endemic goiter areas studied.     

Effects of lactulose and lactitol on coliform bacteria and bacterial translocation in the caecum during 72-h starvation in rats

Lactulose and lactitol, non-absorbable disaccharides, prevent bacterial translocation (BT) arising from the gut. In contrast, lack of food into the gut leads to coliform bacterial overgrowth and even if it does not cause BT, can induce the risk from other stimuli for BT. In this study, we tested whether lactulose and lactitol affected populations of coliform bacteria in the caecum during starvation in Sprague-Dawley rats. Three groups of rats were starved for 72 h and given oral 2 ml undiluted lactulose (670 mg/ml), 2 ml undiluted lactitol (666 mg/ml) or 2 ml physiological saline, respectively, once a day. The caecum and mesenteric lymph nodes (MLNs) were removed for microbiological and histopathological analyses. The highest degree of coliform bacterial overgrowth, BT to MLNs and histopathological damage were observed in lactulose-treated rats, followed by the group treated with lactitol. As a result of this study, both drugs, especially lactulose augmented the proliferation and translocation tendency of coliform bacteria in the caecum during 72-h starvation in rats.     

A biomechanical and spectroscopic study of bone from rats with selenium deficiency and toxicity

Selenium, being an essential mineral in the mammalian diet, is important in providing protection against oxidative damage. Numerous in vitro studies of selenium compounds reveal a very high correlation between catalytic activity of selenium compounds and toxicity. The present study was designed to investigate the effects of dietary selenium on the biomechanical properties of bone. New born rats of both sexes were fed with either a control, or a selenium- and vitamin E-deficient, or a selenium-excess and vitamin E-adequate diet. We obtained the stiffness (modulus of elasticity) of bones (femur and tibia) by tensile test for all groups considered. Both the deficient and the excess groups have decreased biomechanical strength with respect to the control group. To support our biomechanical results for both experimental groups, X-ray diffraction analysis and FTIR spectroscopic study were performed on the femurs and tibiae. The X-ray diffraction analysis showed that the intensities of the peak observed at around 2°=31.820, in the control femur and tibia are stronger than the intensities of the corresponding peak of two experimental groups. In FTIR spectroscopy, the disappearance and/or reduction of the intensities of some carbonate bands in the two experimental groups indicate that there is a decrease in crystallinity and mineral contents which, together with X-ray diffraction analysis, correlate very well with the biomechanical data.     

Opposing Effects of Low Molecular Weight Heparins on the Release of Inflammatory Cytokines from Peripheral Blood Mononuclear Cells of Asthmatics

Background

T-cell-mediated inflammatory cytokines, such as interleukin (IL)-4, IL-5, IL-13 and tumor necrosis factor-alpha (TNF-α), play an important role in the initiation and progression of inflammatory airways diseases. Low-molecular-weight heparins (LMWHs), widely used anticoagulants, possess anti-inflammatory properties making them potential treatment options for inflammatory diseases, including asthma. In the current study, we investigated the modulating effects of two LMWHs (enoxaparin and dalteparin) on the release of cytokines from stimulated peripheral blood mononuclear cells (PBMCs) of asthmatic subjects to identify the specific components responsible for the effects.

Methods

PBMCs from asthmatic subjects (consist of ~75% of T-cells) were isolated from blood taken from ten asthmatic subjects. The PBMCs were pre-treated in the presence or absence of different concentrations of LMWHs, and were then stimulated by phytohaemagglutinin for the release of IL-4, IL-5, IL-13 and TNF-α. LMWHs were completely or selectively desulfated and their anticoagulant effect, as well as the ability to modulate cytokine release, was determined. LMWHs were chromatographically fractionated and each fraction was tested for molecular weight determination along with an assessment of anticoagulant potency and effect on cytokine release.

Results

Enoxaparin inhibited cytokine release by more than 48%, whereas dalteparin increased their release by more than 25%. The observed anti-inflammatory effects of enoxaparin were independent of their anticoagulant activities. Smaller fractions, in particular dp4 (four saccharide units), were responsible for the inhibitory effect of enoxaparin. Whereas, the larger fractions, in particular dp22 (twenty two saccharide units), were associated with the stimulatory effect of dalteparin.

Conclusion

Enoxaparin and dalteparin demonstrated opposing effects on inflammatory markers. These observed effects could be due to the presence of structurally different components in the two LMWHs arising from different methods of depolymerisation. This study provides a platform for further studies investigating the usefulness of enoxaparin in various inflammatory diseases.     

CK2 phosphorylation-dependent interaction between aprataxin and MDC1 in the DNA damage response

Aprataxin, defective in the neurodegenerative disorder ataxia oculomotor apraxia type 1, resolves abortive DNA ligation intermediates during DNA repair. Here, we demonstrate that aprataxin localizes at sites of DNA damage induced by high LET radiation and binds to mediator of DNA-damage checkpoint protein 1 (MDC1/NFBD1) through a phosphorylation-dependent interaction. This interaction is mediated via the aprataxin FHA domain and multiple casein kinase 2 di-phosphorylated S-D-T-D motifs in MDC1. X-ray structural and mutagenic analysis of aprataxin FHA domain, combined with modelling of the pSDpTD peptide interaction suggest an unusual FHA binding mechanism mediated by a cluster of basic residues at and around the canonical pT-docking site. Mutation of aprataxin FHA Arg29 prevented its interaction with MDC1 and recruitment to sites of DNA damage. These results indicate that aprataxin is involved not only in single strand break repair but also in the processing of a subset of double strand breaks presumably through its interaction with MDC1.