Evidence for the onset of color transparency in ρ⁰ electroproduction off nuclei

CLAS Collaboration,El Fassi, L.,Zana, L.,Hafidi, K.,Holtrop, M.,Mustapha, B.,Brooks, W.K.,Hakobyan, H.,Zheng, X.,Adhikari, K.P.,Adikaram, D.,Aghasyan, M.,Amaryan, M.J.,Anghinolfi, M.,Arrington, J.,Ava North-Holland Pub. Co 2012 Physics letters: B Vol.712 No.4

We have measured the nuclear transparency of the incoherent diffractive A(e,e<SUP>'</SUP>ρ<SUP>0</SUP>) process in <SUP>12</SUP>C and <SUP>56</SUP>Fe targets relative to <SUP>2</SUP>H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced ρ<SUP>0</SUP>@?s on a nucleus relative to deuterium, which is sensitive to ρA interaction, was studied as function of the coherence length (l<SUB>c</SUB>), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q<SUP>2</SUP>). While the transparency for both <SUP>12</SUP>C and <SUP>56</SUP>Fe showed no l<SUB>c</SUB> dependence, a significant Q<SUP>2</SUP> dependence was measured, which is consistent with calculations that included the color transparency effects.

Association of chloride-rich fluids and medication diluents on the incidence of hyperchloremia and clinical consequences in aneurysmal subarachnoid hemorrhage

Barlow Brooke,Thompson Bastin Melissa L.,Shadler Aric,Cook Aaron M. 대한신경집중치료학회 2022 대한신경집중치료학회지 Vol.15 No.2

Background: Chloride-rich fluid administration is frequently employed in the management of aneurysmal subarachnoid hemorrhage (aSAH). However, the incidence and consequences of hyperchloremia in aSAH remain poorly defined. This study aimed to describe the incidence of hyperchloremia in aSAH, the contribution of fluid sources to chloride exposure, and the potential associations of hyperchloremia with patient outcomes.Methods: This was a single-center retrospective cohort study of patients admitted to a neurointensive care unit with aSAH. The primary outcome was incidence of hyperchloremia (chloride >109 mEq/L). Secondary outcomes included incidence of severe hyperchloremia (chloride >115 mEq/L), incidence of acute kidney injury (AKI), need for renal replacement therapy (RRT), intensive care unit (ICU) length of stay (LOS), hospital LOS, and in-hospital mortality.Results: Of the 234 patients included in the analysis, hyperchloremia occurred in 75% (n=175), and 58% (n=101) developed severe hyperchloremia. Median time to onset was 3 days (interquartile range, 1–5) after admission. Hyperchloremia was associated with prolonged ICU LOS (12 vs. 8 days, P<0.001), duration of mechanical ventilation (16 vs. 10 days, P<0.001), hospital LOS (15 vs. 9 days, P<0.001), and in-hospital mortality (14.3% vs. 0%, P=0.002) compared to no hyperchloremia. No significant difference was observed in the incidence of AKI or the need for RRT. Maintenance intravenous fluids accounted for the highest proportion of the cumulative chloride burden.Conclusion: Hyperchloremia occurs at a high frequency in aSAH and is associated with poor patient outcomes. Maintenance intravenous fluids accounted for the highest proportion of cumulative chloride burden.

Optimized Methods for the Isolation of Arabidopsis Female Central Cells and Their Nuclei

Park, Kyunghyuk,Frost, Jennifer M.,Adair, Adam James,Kim, Dong Min,Yun, Hyein,Brooks, Janie S.,Fischer, Robert L.,Choi, Yeonhee Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.10

The Arabidopsis female gametophyte contains seven cells with eight haploid nuclei buried within layers of sporophytic tissue. Following double fertilization, the egg and central cells of the gametophyte develop into the embryo and endosperm of the seed, respectively. The epigenetic status of the central cell has long presented an enigma due both to its inaccessibility, and the fascinating epigenome of the endosperm, thought to have been inherited from the central cell following activity of the DEMETER demethylase enzyme, prior to fertilization. Here, we present for the first time, a method to isolate pure populations of Arabidopsis central cell nuclei. Utilizing a protocol designed to isolate leaf mesophyll protoplasts, we systematically optimized each step in order to efficiently separate central cells from the female gametophyte. We use initial manual pistil dissection followed by the derivation of central cell protoplasts, during which process the central cell emerges from the micropylar pole of the embryo sac. Then, we use a modified version of the Isolation of Nuclei TAgged in specific Cell Types (INTACT) protocol to purify central cell nuclei, resulting in a purity of 75-90% and a yield sufficient to undertake downstream molecular analyses. We find that the process is highly dependent on the health of the original plant tissue used, and the efficiency of protoplasting solution infiltration into the gametophyte. By isolating pure central cell populations, we have enabled elucidation of the physiology of this rare cell type, which in the future will provide novel insights into Arabidopsis reproduction.

Measurement of Ratios of νμ Charged-Current Cross Sections on C, Fe, and Pb to CH at Neutrino Energies 2-20 GeV

Tice, B. G.,Datta, M.,Mousseau, J.,Aliaga, L.,Altinok, O.,Barrios Sazo, M. G.,Betancourt, M.,Bodek, A.,Bravar, A.,Brooks, W. K.,Budd, H.,Bustamante, M. J.,Butkevich, A.,Martinez Caicedo, D. A.,Castrom American Physical Society 2014 Physical Review Letters Vol.112 No.23

Effects on Performance of Sulla and/or Maize Silages Supplements for Grazing Dairy Cows

Chaves, Alexandre V.,Woodward, S.L.,Waghorn, G.C.,Brookes, I.M.,Burke, J.L. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.9

The objective of this study was to investigate the effects of either maize or sulla silage supplementation to grazing dairy cows in summer. Forage mixtures used in the four week trial were based on previous experimental results but inclusion of rumen fistulated cows in five treatments enabled rumen sampling and use of in sacco incubations to determine the diet effects on digestion kinetics. Sulla and maize silages were used to supplement pasture and to meet minimum requirements for dietary protein concentration. Five groups of ten cows were grazed on a restricted daily allowance of 18 kg dry matter (DM) pasture/cow to simulate a summer pasture deficit, and four of these five groups received an additional 6 kg DM $cow^{-1}d^{-1}$ of silage (sulla, maize, or sulla and maize silages). A sixth group was given a relatively unrestricted (38 kg DM $cow^{-1}d^{-1}$) pasture allowance. The silage mixtures and pasture were incubated in sacco during the final week of the trial. The pasture was of high nutritive value and not typical of usual summer conditions, which favoured a response to quantity rather than quality of silage supplements. There was no difference in cow performance with the four silage supplements and the low milk solids (MS) production (about 1.0 kg $MS\;d^{-1}$) relative to full pasture (1.3 kg $MS\;d^{-1}$) showed the principal limitation to performance was dry matter intake. Milk composition was not affected by silage type and the low level of pasture substitution (0.29) suggested metabolizable energy (ME) was the principal limitation to performance. Samples of rumen liquor and in sacco data demonstrated significant effects of supplement; DM degradation rates (k) was highest ($0.084h^{-1}$) when cows were fed 6 kg sulla silage whereas diets with a high proportion of maize silage were slowly degraded (p<0.01).

Nucleoporin MOS7/Nup88 is required for mitosis in gametogenesis and seed development in <i>Arabidopsis</i>

Park, Guen Tae,Frost, Jennifer M.,Park, Jin-Sup,Kim, Tae Ho,Lee, Jong Seob,Oh, Sung Aeong,Twell, David,Brooks, Janie Sue,Fischer, Robert L.,Choi, Yeonhee National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.51

<P><B>Significance</B></P><P>During plant reproduction, meiosis generates haploid spores that undergo mitoses, forming gametophytes, in male and female parts of the flower. Haploid cells within gametophytes differentiate into sperm and eggs, which form the next generation. We discovered that the <I>MOS7</I> (Modifier of Snc1,7) gene plays a critical role in microtubule organization and dynamics during mitosis in <I>Arabidopsis</I> sexual reproduction. MOS7 absence results in impaired gametogenesis, failure of ovule and pollen development, and seed abortion. Although mitoses during gamete formation are unique to plants, the regulation of mitosis itself is highly conserved between plants and vertebrates. Notably, we find that MOS7 protein primarily produced prior to meiosis is inherited by gametophytes, and, only if there is sufficient MOS7 protein, will mitosis correctly occur during gametogenesis.</P><P>Angiosperm reproduction is characterized by alternate diploid sporophytic and haploid gametophytic generations. Gametogenesis shares similarities with that of animals except for the formation of the gametophyte, whereby haploid cells undergo several rounds of postmeiotic mitosis to form gametes and the accessory cells required for successful reproduction. The mechanisms regulating gametophyte development in angiosperms are incompletely understood. Here, we show that the nucleoporin Nup88-homolog MOS7 (Modifier of Snc1,7) plays a crucial role in mitosis during both male and female gametophyte formation in <I>Arabidopsis thaliana</I>. Using a mutagenesis screen, we identify the <I>mos7-5</I> mutant allele, which causes ovule and pollen abortion in <I>MOS7/mos7-5</I> heterozygous plants, and preglobular stage embryonic lethality in homozygous <I>mos7-5</I> seeds. During interphase, we show that MOS7 is localized to the nuclear membrane but, like many nucleoporins, is associated with the spindle apparatus during mitosis. We detect interactions between MOS7 and several nucleoporins known to control spindle dynamics, and find that in pollen from <I>MOS7</I>/<I>mos7-5</I> heterozygotes, abortion is accompanied by a failure of spindle formation, cell fate specification, and phragmoplast activity. Most intriguingly, we show that following gamete formation by <I>MOS7/mos7-5</I> heterozygous spores, inheritance of either the <I>MOS7</I> or the <I>mos7-5</I> allele by a given gamete does not correlate with its respective survival or abortion. Instead, we suggest a model whereby MOS7, which is highly expressed in the Pollen- and Megaspore Mother Cells, enacts a dosage-limiting effect on the gametes to enable their progression through subsequent mitoses.</P>

Control of DEMETER DNA demethylase gene transcription in male and female gamete companion cells in <i>Arabidopsis thaliana</i>

Park, Jin-Sup,Frost, Jennifer M.,Park, Kyunghyuk,Ohr, Hyonhwa,Park, Guen Tae,Kim, Seohyun,Eom, Hyunjoo,Lee, Ilha,Brooks, Janie S.,Fischer, Robert L.,Choi, Yeonhee National Academy of Sciences 2017 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.114 No.8

<P>The DEMETER (DME) DNA glycosylase initiates active DNA demethy-lation via the base-excision repair pathway and is vital for reproduction in Arabidopsis thaliana. DME-mediated DNA demethylation is preferentially targeted to small, AT-rich, and nucleosome-depleted euchromatic transposable elements, influencing expression of adjacent genes and leading to imprinting in the endosperm. In the female gametophyte, DME expression and subsequent genome-wide DNA demethylation are confined to the companion cell of the egg, the central cell. Here, we show that, in the male gametophyte, DME expression is limited to the companion cell of sperm, the vegetative cell, and to a narrow window of time: immediately after separation of the companion cell lineage from the germline. We define transcriptional regulatory elements of DME using reporter genes, showing that a small region, which surprisingly lies within the DME gene, controls its expression in male and female companion cells. DME expression from this minimal promoter is sufficient to rescue seed abortion and the aberrant DNA methylome associated with the null dme-2 mutation. Within this minimal promoter, we found short, conserved enhancer sequences necessary for the transcriptional activities of DME and combined predicted binding motifs with published transcription factor binding coordinates to produce a list of candidate upstream pathway members in the genetic circuitry controlling DNA demethylation in gamete companion cells. These data show how DNA demethylation is regulated to facilitate endosperm gene imprinting and potential transgenerational epigenetic regulation, without subjecting the germline to potentially deleterious transposable element demethylation.</P>

Gender and telomere length: Systematic review and meta-analysis

the Halcyon study team,Gardner, M.,Bann, D.,Wiley, L.,Cooper, R.,Hardy, R.,Nitsch, D.,Martin-Ruiz, C.,Shiels, P.,Sayer, A.A.,Barbieri, M.,Bekaert, S.,Bischoff, C.,Brooks-Wilson, A.,Chen, W.,Cooper, C. Pergamon Press ; Elsevier Science Ltd 2014 Experimental Gerontology Vol.51 No.-

Background: It is widely believed that females have longer telomeres than males, although results from studies have been contradictory. Methods: We carried out a systematic review and meta-analyses to test the hypothesis that in humans, females have longer telomeres than males and that this association becomes stronger with increasing age. Searches were conducted in EMBASE and MEDLINE (by November 2009) and additional datasets were obtained from study investigators. Eligible observational studies measured telomeres for both females and males of any age, had a minimum sample size of 100 and included participants not part of a diseased group. We calculated summary estimates using random-effects meta-analyses. Heterogeneity between studies was investigated using sub-group analysis and meta-regression. Results: Meta-analyses from 36 cohorts (36,230 participants) showed that on average females had longer telomeres than males (standardised difference in telomere length between females and males 0.090, 95% CI 0.015, 0.166; age-adjusted). There was little evidence that these associations varied by age group (p=1.00) or cell type (p=0.29). However, the size of this difference did vary by measurement methods, with only Southern blot but neither real-time PCR nor Flow-FISH showing a significant difference. This difference was not associated with random measurement error. Conclusions: Telomere length is longer in females than males, although this difference was not universally found in studies that did not use Southern blot methods. Further research on explanations for the methodological differences is required.

Optimized Methods for the Isolation of Arabidopsis Female Central Cells and Their Nuclei

Yeonhee Choi,Kyunghyuk Park,Jennifer M. Frost,Adam James Adair,Dong Min Kim,Hyein Yun,Janie S. Brooks,Robert L. Fischer 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.10

The Arabidopsis female gametophyte contains seven cells with eight haploid nuclei buried within layers of sporophytic tissue. Following double fertilization, the egg and central cells of the gametophyte develop into the embryo and endosperm of the seed, respectively. The epigenetic status of the central cell has long presented an enigma due both to its inaccessibility, and the fascinating epigenome of the endosperm, thought to have been inherited from the central cell following activity of the DEMETER demethylase enzyme, prior to fertilization. Here, we present for the first time, a method to isolate pure populations of Arabidopsis central cell nuclei. Utilizing a protocol designed to isolate leaf mesophyll protoplasts, we systematically optimized each step in order to efficiently separate central cells from the female gametophyte. We use initial manual pistil dis-section followed by the derivation of central cell proto-plasts, during which process the central cell emerges from the micropylar pole of the embryo sac. Then, we use a modified version of the Isolation of Nuclei TAgged in specific Cell Types (INTACT) protocol to purify central cell nuclei, resulting in a purity of 75-90% and a yield sufficient to undertake downstream molecular analyses. We find that the process is highly dependent on the health of the original plant tissue used, and the efficiency of protoplasting solution infiltration into the gametophyte. By isolating pure central cell populations, we have enabled elucidation of the physiology of this rare cell type, which in the future will provide novel insights into Arabidopsis reproduction.

Recruitment of Rod Photoreceptors from Short-Wavelength-Sensitive Cones during the Evolution of Nocturnal Vision in Mammals

Kim, J.W.,Yang, H.J.,Oel, A.,Brooks, M.,Jia, L.,Plachetzki, D.,Li, W.,Allison, W.,Swaroop, A. Cell Press 2016 DEVELOPMENTAL CELL Vol.37 No.6

<P>Vertebrate ancestors had only cone-like photoreceptors. The duplex retina evolved in jawless vertebrates with the advent of highly photosensitive rod-like photoreceptors. Despite cones being the arbiters of high-resolution color vision, rods emerged as the dominant photoreceptor in mammals during a nocturnal phase early in their evolution. We investigated the evolutionary and developmental origins of rods in two divergent vertebrate retinas. In mice, we discovered genetic and epigenetic vestiges of short-wavelength cones in developing rods, and cell-lineage tracing validated the genesis of rods from S cones. Curiously, rods did not derive from S cones in zebrafish. Our study illuminates several questions regarding the evolution of duplex retina and supports the hypothesis that, in mammals, the S-cone lineage was recruited via the Maf-family transcription factor NRL to augment rod photoreceptors. We propose that this developmental mechanism allowed the adaptive exploitation of scotopic niches during the nocturnal bottleneck early in mammalian evolution.</P>