Effect of CO2 on carbonic anhydrase in Avena sativa and Zea mays

In leaves of Zea mays kept in air with reduced or increased CO₂, the level of carbonic anhydrase is reduced or increased respectively. In Avena sativa an opposite effect of pCO₂ is observed. In both cases the enzyme activity rapidly reached normal values when the plants were transferred back to normal atmosphere.     

Effect of Lincocin Treatment on the Greening Process in Bean (Phaseolus vulgaris) Leaves

The effect of lincocin (a plastid protein synthesis inhibitor) treatment on the greening process of bean (Phaseolus vulgaris L.) leaves have been studied. In comparison with control leaves treated ones had a decreased rate of chloroplast development. They had a marked chlorophyll deficiency and a decreased chlorophyll a/b ratio. Some long and short wavelength forms of chlorophyll a were lacking as evidenced from the absorption spectra at 25°C and the fluorescence spectra at 77°K. The –¹⁴CO₂ fixation was inhibited by 80–90% in treated leaves. The fluorescence induced by the measuring light was greater in the treated leaves than in the control ones, and the kinetics of the decline of the relative fluorescence intensity were also different. Electron microscopic studies showed macrogranum-like structures and incomplete membrane vesicles in the treated plastids. After longer treatment a destruction of membranes was observed. The results indicate some structural and functional membrane deficiencies and instability of the membranes.     

A Highlights from MBoC Selection: Golgi Partitioning Controls Mitotic Entry through Aurora-A Kinase

At the onset of mitosis, the Golgi complex undergoes a multistep fragmentation process that is required for its correct partitioning into the daughter cells. Inhibition of this Golgi fragmentation results in cell cycle arrest at the G2 stage, suggesting that correct inheritance of the Golgi complex is monitored by a “Golgi mitotic checkpoint.” However, the molecular basis of this G2 block is not known. Here, we show that the G2-specific Golgi fragmentation stage is concomitant with centrosome recruitment and activation of the mitotic kinase Aurora-A, an essential regulator for entry into mitosis. We show that a block of Golgi partitioning impairs centrosome recruitment and activation of Aurora-A, which results in the G2 block of cell cycle progression. Overexpression of Aurora-A overrides this cell cycle block, indicating that Aurora-A is a major effector of the Golgi checkpoint. Our findings provide the basis for further understanding of the signaling pathways that coordinate organelle inheritance and cell duplication.     

Golgi complex fragmentation in G2/M transition: An organelle-based cell-cycle checkpoint

In mammalian cells, the Golgi complex is organized into a continuous membranous system known as the Golgi ribbon, which is formed by individual Golgi stacks that are laterally connected by tubular bridges. During mitosis, the Golgi ribbon undergoes extensive fragmentation through a multistage process that is required for its correct partitioning into the daughter cells. Importantly, inhibition of this Golgi disassembly results in cell-cycle arrest at the G2 stage, suggesting that accurate inheritance of the Golgi complex is monitored by a "Golgi mitotic checkpoint." Here, we discuss the mechanisms and regulation of the Golgi ribbon breakdown and briefly comment on how Golgi partitioning may inhibit G2/M transition.     

Adult spinal opioid receptor μ1 expression after incision is altered by early life repetitive tactile and noxious procedures in rats

Clinical and experimental data suggests that noxious stimulation at critical stages of development results in long‐term changes on nociceptive processing in later life. Here, we use an established, well‐documented rat model of repetitive noxious procedures closely mimicking the clinical situation in the NICU. In order to understand molecular changes underlying the long‐term consequences of repetitive stimulation of the developing nociceptive system the present study aims to analyze the presence of the µ‐opioid‐receptor‐1 (OPRM1). Neonatal rats received either four needle pricks per day in the left hind‐paw from postnatal day 0–7 as a model of procedural pain in infancy. Control pups were handled in the same way but were instead tactile stimulated, or were left undisturbed. At the age of 8 weeks, all animals received an ipsilateral hind‐paw incision as a model for post‐operative pain, and mechanical sensitivity was tested at multiple time‐points. Before, and 1 or 5 days post‐incision, spinal cord tissue was collected for immunostaining of opioid receptor OPRM1. Semi‐quantitative immunocytochemical analysis of superficial laminae in lumbar spinal dorsal horn revealed that: (1) early life repetitive tactile or noxious procedures do not alter baseline levels of OPRM1 staining intensity and (2) early life repetitive tactile or noxious procedures lead to a decrease in OPRM1 staining intensity 5 days after incision in adulthood compared to undisturbed controls. We conclude that early life repetitive tactile or noxious procedures affect the intensity of OPRM1‐immunoreactivity in the lumbar superficial spinal cord dorsal horn after adulthood injury, without affecting baseline intensity. © 2018 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol 78: 417–426, 2018     

Variation in cytosine methylation patterns during ploidy level conversions in Eragrostis curvula

In many species polyploidization involves rearrangements of the progenitor genomes, at both genetic and epigenetic levels. We analyzed the cytosine methylation status in a ‘tetraploid-diploid-tetraploid’ series of Eragrostis curvula with a common genetic background by using the MSAP (Methylation-sensitive Amplified Polymorphism) technique. Considerable levels of polymorphisms were detected during ploidy conversions. The total level of methylation observed was lower in the diploid genotype compared to the tetraploid ones. A significant proportion of the epigenetic modifications occurring during the tetraploid–diploid conversion reverted during the diploid–tetraploid one. Genetic and expression data from previous work were used to analyze correlation with methylation variation. All genetic, epigenetic and gene expression variation data correlated significantly when compared by pairs in simple Mantel tests. Dendrograms reflecting genetic, epigenetic and expression distances as well as principal coordinate analysis suggested that plants of identical ploidy levels present similar sets of data. Twelve (12) different genomic fragments displaying different methylation behavior during the ploidy conversions were isolated, sequenced and characterized.     

Ricerche Sulle Sostanze Alchilanti Mutagene

Abstract

Researches on alkylating chemicals mutagens (method of treatment with diethyl sulfate. — The problem of the treatment of seeds with alkylating agents, belonging to the categories of alkylsuphonic and sulphuric esters, was investigated from a chemical and methodological viewpoint.

After a determination of the hydrolisis constants and of the activation energies of some compounds, diethylsulphate, undergoing hydrolisis most rapidly and — consequently — being the least appropriate for use in solution, was chosen for treatment of durum wheat seeds (cv. « Cappelli »). Using treatments of different durations with solutions of different concentrations under several temperature conditions, the amounts of diethylsulphate and of ethylsulfuric acid (one of the hydrolisis products) absorbed per seed in each treatment were calculated. In addition, the effect of the two fractions on seed germinability was studied.

Since the threshold value of the germination inhibiting effect of ethylsulfuric acid was fixed at 8.10^?8 moles absorbed per seed, treatments could be found which allowed absorption of increasing doses of the ester by keeping absorption of the acid below the toxicity threshold. This was attained by varying properly the conditions of treatment (dose, duration and temperature). It could be demonstrated that, at identical amounts of ester absorbed per seed, an identical effect of germination took place, indipendently of type of treatment.

The need for an accurate measurement of the absorbed dose in studies on dose-effect relations with chemical mutagens is stressed.     

Effetto dell'Irraggiamento X sulla Biosintesi degli Amminoacidi in Piante di Orzo

Abstract

The effects of irradiation on aminoacids biosynthesis in barley. — The effect of radiations on the biosynthesis of aminoacids in barley has been studied. Seeds have been irradiated with X-tays of 7.5 and seedlings with 7.5, 15 and 30 Kr. After 6–7 days of growth the control and irradiated seedlings, and the seedlings from control and irradiated seeds, have been supplied with 10–100 μC of C¹⁴O₂ in a closed chamber for 44–42 hours. The material was extracted with hot ethanol (85%–80% and 40%). Total radioactivity and the radioactivity of the basic fraction, eluted with HCl from Dowex 50, X-8′ (200–400 mesh, H^?) have been measured. It was observed that radiations increase the radioactivity of the aminoacid fraction, both in leaves and roots. A correlation between the decrease of fresh weight and increase of aminoacids radioactivity was shown. A possible explanation might be visualized in terms of the inhibition of growth and protein synthesis by radiations.     

Mapping of main and epistatic effect QTLs associated to grain protein and gluten strength using a RIL population of durum wheat

Quality, specifically protein content and gluten strength are among the main objectives of a durum wheat breeding program. The aim of this work was to validate quantitative trait loci (QTLs) associated with grain protein content (GPC) and gluten strength measured by SDS sedimentation volume (SV) and to find additional QTLs expressed in Argentinean environments. Also, epistatic QTL and QTL x environmental interactions were analyzed. A mapping population of 93 RILs derived from the cross UC1113 x Kofa showing extreme values in gluten quality was used. Phenotypic data were collected along six environments (three locations, two years). Main effect QTLs associated with GPC were found in equivalent positions in two environments on chromosomes 3BS (R² = 21.0-21.6%) and 7BL (R² = 12.1-13%), and in one environment on chromosomes 1BS, 2AL, 2BS, 3BL, 4AL, 5AS, 5BL and 7AS. The most important and stable QTL affecting SV was located on chromosome 1BL (Glu-B1) consistently detected over the six environments (R² = 20.9- 54.2%). Additional QTLs were found in three environments on chromosomes 6AL (R² = 6.4-12.5%), and in two environments on chromosomes 6BL (R² = 11.5-12.1%), 7AS (R² = 8.2-10.2%) and 4BS (R² = 11–16.4%). In addition, pleiotropic effects were found affecting grain yield, test weight, thousand-kernel- weight and days to heading in some of these QTLs. Epistatic QTLs and QTL x environment interactions were found for both quality traits, mostly for GPC. The flanking markers of the QTLs detected in this work could be efficient tools to select superior genotypes for the mentioned traits.