Temperature Effects on the Activation and Inactivation of Pyruvate, Pi Dikinase in Two Populations of the C4 Weed Echinochloa crus-galli (Barnyard Grass) From Sites of Contrasting Climates

1994 ◽  
Vol 21 (4) ◽  
pp. 463 ◽  
Author(s):  
JP Simon ◽  
MD Hatch
Keyword(s):  
Temperature Effects ◽  
C4 Photosynthesis ◽  
Cold Sensitivity ◽  
Significant Finding ◽  
Initial Activity ◽  
Barnyard Grass ◽  
Two Populations ◽  
Cold Inactivation ◽  
Rate Of Activation

Five-week-old plants of Echinochloa crus-galli (L.) Beauv. (barnyard grass) from Mississippi (MISS) and from Québec (QUE) grown under controlled conditions were subjected to cold temperature acclimatory treatments for periods of up to 3 days. After plants were transferred from a 26/20�C day/night regime to 14/8�C for 2-3 days the rate of activation of the C4 photosynthetic enzyme pyruvate, Pi dikinase (PPDK; EC 2.7.9.1), following illumination of plants at 26�C, was substantially reduced in both ecotypes. This effect was far more pronounced in MISS plants and the PPDK activity of these plants remained at less than half that of control plants (26/20�C) even after 2 h illumination. After 3 days at 14/8�C the half-time for PPDK activation was more than 120 min in MISS plants and 35 min in QUE plants compared with about 3 min for plants remaining in the 26/20�C regime. Lesser but qualitatively similar effects were observed when plants were exposed to only cooler nights (26/8�C) or cooler days (14/20�C). When plants at the 14/8�C regime were transferred back to 26/20�C for 2 days there was a substantial recovery of the capacity for rapid PPDK activation but recovery was slower in MISS plants. Predictably, the rate of activation of PPDK was reduced when activation in control plants (26/20�C) was carried out at 8�C instead of 26�C. However, a significant finding was that the rate of activation at 8�C was more strongly affected in MISS plants, with a reduction to about 15% of the rate of control plants and a final steady PPDK level after 60 min of only half that in control plants. PPDK extracted from MISS plants underwent more rapid in vitro cold inactivation (2�C) than the enzyme from QUE plants and only 80% of the initial activity was recovered upon rewarming at 25�C. The physiological significance of these results are discussed in relation to the cold sensitivity of C4 photosynthesis and the previously reported differences in the growth and physiological performance of MISS and QUE plants at lower temperatures.

Molecular forms and thermal and kinetic properties of purified glutathione reductase from two populations of barnyard grass (Echinochloa crus-galli(L.) Beauv.: Poaceae) from contrasting climatic regions in North America

2000 ◽  
Vol 78 (7) ◽  
pp. 969-980 ◽  
Author(s):  
Nadia Hakam ◽  
Jean-Pierre Simon
Keyword(s):  
Glutathione Reductase ◽  
Thermal Adaptation ◽  
Catalytic Efficiency ◽  
Molecular Forms ◽  
Kinetic Properties ◽  
Barnyard Grass ◽  
Climatic Regions ◽  
Two Populations ◽  
Menten Constant

The thermal, kinetic, and electrophoretic properties of purified glutathione reductase (GR; EC 1.6.4.2) were analyzed in plants from two ecotypes of barnyard grass (Echinochloa crus-galli (L.) Beauv.: Poaceae) originating from sites of contrasting climates in Quebec (QUE) and Mississippi (MISS). Crude and purified GR preparations from plants of both ecotypes consisted of one homodimer isomorph with the same electrophoretic mobility in polyacrylamide gels, a similar molecular mass for the native enzyme (98 kDa) and for each subunit of the dimer (44 kDa), and an identical pI of 5.9. The electrophoretic profile of GR purified from cold-acclimated plants at 14°C light (L) : 8°C dark (D) for 10 days was similar to that of GR from plants grown at 26°C L : 20°C D. Specific activities of purified GR from QUE plants were significantly higher than those of MISS plants. In vitro GR activities from QUE and MISS plants were not differentially affected by thermodenaturation at 55 or 65°C or by cold treatments at 2°C. Apparent energies of activation (Ea) of GR purified from QUE and MISS plants were similar with the exception of estimates of Ea(oxidized glutathione) for Q10(15-5°C) for which significantly lower values were obtained for QUE plants. No differences of physiological significance were observed for Km(Michaelis-Menten constant) values of GR purified from QUE and MISS plants. However, both Vmaxand Kcat(turnover numbers) estimates were significantly higher for GR purified from QUE plants over most of the range of assay temperatures, suggesting superior catalytic efficiency for the enzyme of the cold-adapted ecotype from Québec.Key words: barnyard grass, ecotypes, electrophoresis, enzyme kinetics, glutathione reductase, thermal adaptation.

scholarly journals Reversible ATP-induced inactivation of branched-chain 2-oxo acid dehydrogenase

1980 ◽  
Vol 192 (1) ◽  
pp. 155-163 ◽  
Author(s):  
R Odessey
Keyword(s):  
Skeletal Muscle ◽  
Liver Mitochondria ◽  
Initial Activity ◽  
Rat Skeletal Muscle ◽  
Kidney Mitochondria ◽  
Physiological Conditions ◽  
Acid Dehydrogenase ◽  
Skeletal Muscle Mitochondria ◽  
Branched Chain

The branched chain 2-oxo acid dehydrogenase from rat skeletal muscle, heart, kidney and liver mitochondria can undergo a reversible activation-inactivation cycle in vitro. Similar results were obtained with the enzyme from kidney mitochondria of pig and cow. The dehydrogenase is markedly inhibited by ATP and the inhibition is not reversed by removing the nucleotide. The non-metabolizable ATP analogue adenosine 5′-[beta gamma-imido] triphosphate can block the effect of ATP when added with the nucleotide, but has no effect by itself, nor can it reverse the inhibition in mitochondria preincubated with ATP. These findings suggest that the branched chain 2-oxo acid dehydrogenase undergoes a stable modification that requires the splitting of the ATP gamma-phosphate group. In skeletal muscle mitochondria the rate of inhibition by ATP is decreased by oxo acid substrates and enhanced by NADH. The dehydrogenase can be reactivated 10-20 fold by incubation at pH 7.8 in a buffer containing Mg2+ and cofactors. Reactivation is blocked by NaF (25 mM). The initial activity of dehydrogenase extracted from various tissues of fed rats varies considerably. Activity is near maximal in kidney and liver whereas the dehydrogenase in heart and skeletal muscle is almost completely inactivated. These studies emphasize that comparisons of branched chain 2-oxo acid dehydrogenase activity under various physiological conditions or in different tissues must take into account its state of activation. Thus the possibility exists that the branched chain 2-oxo acid dehydrogenase may be physiologically regulated via a covalent mechanism.

scholarly journals Super Cooling Point Phenotypes and Cold Resistance in Hyles euphorbiae Hawk Moths from Different Climate Zones

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 207
Author(s):  
Hana Daneck ◽  
Matthias Benjamin Barth ◽  
Martin Geck ◽  
Anna K. Hundsdoerfer
Keyword(s):  
Environmental Conditions ◽  
Cold Hardiness ◽  
Cold Treatment ◽  
Underlying Mechanism ◽  
Frost Tolerance ◽  
Cold Sensitivity ◽  
Cold Hardy ◽  
Hyles Euphorbiae

The spurge hawkmoth Hyles euphorbiae L. (Sphingidae) comprises a remarkable species complex with still not fully resolved taxonomy. Its extensive natural distribution range covers diverse climatic zones. This predestinates particular populations to cope with different local seasonally unfavorable environmental conditions. The ability of the pupae to overcome outer frosty conditions is well known. However, the differences between two main ecotypes (‘euphorbiae’ and ‘tithymali’) in terms of the inherent degree of frost tolerance, its corresponding survival strategy, and underlying mechanism have not been studied in detail so far. The main aim of our study was to test the phenotypic exhibition of pupae (as the relevant life cycle stadia to outlast unfavorable conditions) in response to combined effects of exogenous stimuli, such as daylight length and cooling regime. Namely, we tested the turnout of subitan (with fast development, unadapted to unfavorable conditions) or diapause (paused development, adapted to unfavorable external influences and increased resistance) pupae under different conditions, as well as their mortality, and we measured the super cooling point (SCP) of whole pupae (in vivo) and pupal hemolymph (in vitro) as phenotypic indicators of cold acclimation. Our results show higher cold sensitivity in ‘tithymali’ populations, exhibiting rather opportunistic and short-termed cold hardiness, while ‘euphorbiae’ produces a phenotype of seasonal cold-hardy diapause pupae under a combined effect of short daylight length and continuous cold treatment. Further differences include the variability in duration and mortality of diapause pupae. This suggests different pre-adaptations to seasonal environmental conditions in each ecotype and may indicate a state of incipient speciation within the H. euphorbiae complex.

scholarly journals Investigating the Intrafollicular Factors Affecting Oocyte Developmental Competency

2021 ◽  
Author(s):  
◽  
Zaramasina Clark
Keyword(s):  
Gene Expression ◽  
Oocyte Maturation ◽  
Granulosa Cells ◽  
Embryo Quality ◽  
Cumulus Cells ◽  
Significant Finding ◽  
High Quality ◽  
Final Maturation

<p>The number of cycles of assisted reproductive technologies (ART) performed increased by ~9.5 % globally between 2008 and 2010. In spite of this, the success rate in terms of delivery was only ~19.0 % (Dyer et al., 2016). This discrepancy between the demand for, and success of, these technologies necessitates the development of tools to improve ART efficiency. To facilitate this, a better understanding of how the microenvironment changes within the developing follicle to culminate in a mature, developmentally-competent oocyte is required. This study employed an in vivo and in vitro ovine model to investigate the relationship between the surrounding microenvironment and oocyte maturation, and in particular, the attainment of oocyte developmental competency and high-quality embryos.  The first objective of this PhD study was to comprehensively investigate the changing microenvironment of in vivo matured, presumptive preovulatory (PPOV) follicles from wild-type (++) and high ovulation rate (OR; I+B+) ewes. The high OR ewes were heterozygous carriers of mutations in BMP15 (I+) and BMPRIB (B+). Functional differences in follicular somatic (granulosa and cumulus) cells between these genotypes, including differential gonadotropin responsiveness of granulosa cells, composition of follicular fluid and gene expression profiles in cumulus cells were evident. These differences emerged as part of a compensatory mechanism by which oocytes from smaller follicles, containing fewer granulosa cells, achieved developmental competency in I+B+ ewes.  The second objective of this PhD study was to develop new approaches for improving current in vitro maturation (IVM) strategies. The first approach utilised in this study focused on developing biomarkers that could be used to improve prediction of developmental competency in oocytes and in vitro produced embryos. This involved interrogating the hypothesis that a combination of molecular and morphokinetic biomarkers would better predict the developmental competency of oocytes and embryos compared to using these biomarkers alone. The second approach utilised in this PhD study tested the effects of modulating IVM conditions to better mimic the follicular microenvironment of a high, compared to a low, OR species on oocyte developmental competency and embryo quality. This involved supplementing IVM media with different ratios of two oocyte-secreted growth factors, i.e. GDF9:BMP15, that were representative of low or high OR species. These approaches demonstrated significant potential and warrant further investigation.  The most significant finding of this study was that despite variances in the surrounding microenvironment during in vivo and in vitro oocyte maturation that culminated in differential gene expression patterns in cumulus cells, and divergent gonadotropin-responsiveness of granulosa cells, the gene expression signatures of developmentally-competent oocytes and the morphokinetics of high-quality embryos were unaltered. This confirms the value of developing such biomarkers for oocyte development competency and embryo quality that remain unaltered despite a changing surrounding environment. Interestingly, simulating the ratio of GDF9:BMP15 that oocytes from high OR species are exposed to during maturation improved developmental competency in oocytes as demonstrated by increased blastocyst rates. Furthermore, this study has demonstrated that combinations of molecular (cumulus cell gene expression) and morphokinetic biomarkers improved the ability to predict developmental competency in oocytes and embryos. Overall, this study revealed novel information regarding the follicular microenvironment during final maturation and identified several novel approaches to improving the efficiency of ART.</p>

ADP ribosylation factor is an essential protein in Saccharomyces cerevisiae and is encoded by two genes

1990 ◽  
Vol 10 (12) ◽  
pp. 6690-6699
Author(s):  
T Stearns ◽  
R A Kahn ◽  
D Botstein ◽  
M A Hoyt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cold Sensitivity ◽  
Animal Cells ◽  
Gene Encoding ◽  
Phenotypic Differences ◽  
Adp Ribosylation ◽  
Protein Factor ◽  
Adp Ribosylation Factor ◽  
Sublethal Concentrations

ADP ribosylation factor (ARF) is a ubiquitous 21-kDa GTP-binding protein in eucaryotes. ARF was first identified in animal cells as the protein factor required for the efficient ADP-ribosylation of the mammalian G protein Gs by cholera toxin in vitro. A gene (ARF1) encoding a protein homologous to mammalian ARF was recently cloned from Saccharomyces cerevisiae (Sewell and Kahn, Proc. Natl. Acad. Sci. USA, 85:4620-4624, 1988). We have found a second gene encoding ARF in S. cerevisiae, ARF2. The two ARF genes are within 28 centimorgans of each other on chromosome IV, and the proteins encoded by them are 96% identical. Disruption of ARF1 causes slow growth, cold sensitivity, and sensitivity to normally sublethal concentrations of fluoride ion in the medium. Disruption of ARF2 causes no detectable phenotype. Disruption of both genes is lethal; thus, ARF is essential for mitotic growth. The ARF1 and ARF2 proteins are functionally homologous, and the phenotypic differences between mutations in the two genes can be accounted for by the level of expression; ARF1 produces approximately 90% of total ARF. Among revertants of the fluoride sensitivity of an arf1 null mutation were ARF1-ARF2 fusion genes created by a gene conversion event in which the deleted ARF1 sequences were repaired by recombination with ARF2.

Culture of goat preantral follicles in situ associated with mesenchymal stem cell from bone marrow

Zygote ◽  
2019 ◽  
Vol 28 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Camila Arrivabene Neves ◽  
Lucilene dos Santos Silva ◽  
Camila Ernanda Sousa de Carvalho ◽  
Marina Silva Carvalho ◽  
José Lindenberg Rocha Sarmento ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Culture Medium ◽  
Reduced Glutathione ◽  
Follicular Growth ◽  
Morphological Classification ◽  
Nitrite Concentration ◽  
Preantral Follicles ◽  
Rate Of Activation

SummaryThis study aims to develop an in vitro co-culture system of in situ goat preantral follicles with bone marrow-derived mesenchymal stem cells (BM-MSC), evaluating the influence of these cells on follicular growth, rate of activation and morphologically normal follicles. Fragments of ovarian cortex were cultured for 1 or 7 days in the presence of BM-MSC (BM-MSC+) and absence of BM-MSC (BM-MSC−). Histological sections of the fragments were analysed and data were obtained regarding morphological classification, survival rate of morphologically normal follicles and rate of follicular activation. Culture medium on days 1 and 7 was also sampled for nitrite concentration and reduced glutathione activity. There was a reduction (P < 0.05) in the percentage of morphologically normal follicles in the BM-MSC+ compared with the fresh control only on the seventh day of culture. When comparing treatments, on the seventh day of culture, a higher rate of morphologically normal preantral follicles was observed in BM-MSC+ (P < 0.05). In both treatments, primordial and developing follicle rates were similar to the fresh control (P > 0.05). When comparing treatments with each other, as well as with the fresh control, no differences were observed in follicular diameter (P > 0.05) or nitrite concentration (P > 0.05). The concentration of reduced glutathione was lower on the seventh day of co-culture in both treatments (P < 0.05). In conclusion, co-culture had no influence on follicular or oocyte development. However, it was critical to maintain the survival of preantral follicles during 7 days of culture.

Arteriolar endothelial cell barrier separates two populations of muscarinic receptors

1992 ◽  
Vol 262 (4) ◽  
pp. H1311-H1315 ◽  
Author(s):  
R. J. Rivers ◽  
B. R. Duling
Keyword(s):  
Endothelial Cell ◽  
Muscarinic Receptors ◽  
Vessel Wall ◽  
Cheek Pouch ◽  
Different Populations ◽  
Differential Control ◽  
Two Sides ◽  
Two Populations

The endothelium of arterioles can function as a barrier to diffusion of hydrophilic molecules when studied in vitro. Thus a substance applied to one side of the arteriole is relatively ineffective in reaching receptors on the opposite side of the vessel wall unless it is lipid soluble. To study the receptor populations on the two sides of the arteriolar endothelium, we used micropipettes to apply methacholine (MCh; 1.0 microM), either luminally or adventitially, for 5 s to the arterioles of the cheek pouch of pentobarbital-anesthetized hamsters. MCh equally dilated the arterioles regardless of the side of application. That different populations of receptors are located on either side of the arteriole was shown by the fact that adventitially applied hydrophilic methscopolamine was ineffective in blocking the effects of the luminally applied MCh but completely blocked the effects of abluminally applied MCh. In contrast, the luminal population of receptors was easily blocked by adventially applied scopolamine, which is lipophilic. Separate and independent populations of receptors in the vessel wall suggests the potential for differential control between humoral and adventitial sources of vasoactive metabolites.

Composition and In vitro Antimicrobial Activities of the Essential Oils of Two Populations ofThymus numidicusPoiret

2009 ◽  
Vol 21 (4) ◽  
pp. 374-377 ◽  
Author(s):  
Hocine Laouer ◽  
Nacira Boulaacheb ◽  
Salah Akkal ◽  
Uwe J. Meierhenrich ◽  
Nicolas Baldovini ◽  
...  
Keyword(s):  
Essential Oils ◽  
Antimicrobial Activities ◽  
Two Populations

scholarly journals Isolation, Characterization and Differentiation Potential of Chicken Spermatogonial Stem Cell Derived Embryoid Bodies

2016 ◽  
Vol 16 (1) ◽  
pp. 115-128 ◽  
Author(s):  
Thanh Luan Nguyen ◽  
Jae Gyu Yoo ◽  
Neelesh Sharma ◽  
Sung Woo Kim ◽  
Yong Jun Kang ◽  
...  
Keyword(s):  
Developmental Biology ◽  
Regenerative Medicine ◽  
Connexin 43 ◽  
Es Cells ◽  
Periodic Acid ◽  
Embryonic Stem ◽  
Embryoid Bodies ◽  
Significant Finding ◽  
Differentiation Potential

Abstract Human, murine and monkey spermatogonial stem cells (SSCs) have the capability to undergo self-renewal and differentiation into different body cell types in vitro, which are expected to serve as a powerful tool and resource for the developmental biology and regenerative medicine. We have successfully isolated and characterized the chicken SSCs from 3-day-old chicken testicular cells. The pluripotency was using Periodic Acid-Schiff (PAS ) staining or alkaline phosphatase staining, and antibodies to stage-specific embryonic antigens. In suspension culture conditions SSCs formed embryoid bodies (EBs) like embryonic stem (ES) cells. Subsequently EB differentiated into osteoblasts, adipocytes and most importantly into cardiomyocytes under induced differentiation conditions. The differentiation potential of EBs into cardiomyocyte-like cells was confirmed by using antibodies against sarcomeric α-actinin, cardiac troponin T and connexin 43. Cardiomyocytes-like cells were also confirmed by RT-PCR analysis for several cardiac cell genes like GATA-4, Nkx2-5, α-MHC, and ANF. We have successfully established an in vitro differentiation system for chicken SSCs into different body cells such as osteoblasts, adipocytes and cardiomyocytes. The most significant finding of this study is the differentiation potential of chicken SSCs into cardiomyocytes. Our findings may have implication in developmental biology and regenerative medicine by using chicken as the most potential animal model.

Temperature effects on muscle growth in two populations (Atlantic and Mediterranean) of sea bass, Dicentrarchus labrax L.

Aquaculture ◽  
2001 ◽  
Vol 202 (3-4) ◽  
pp. 359-370 ◽  
Author(s):  
Marı́a D Ayala ◽  
Octavio López-Albors ◽  
Francisco Gil ◽  
Alicia Garcı́a-Alcázar ◽  
Emilia Abellán ◽  
...  
Keyword(s):  
Temperature Effects ◽  
Muscle Growth ◽  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Two Populations
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