The Role of Antioxidants in Modulating Neutrophil Functional Responses

AbstractIn the current study, we investigated the functional response of Harmonia axyridis adults and larvae foraging on Acyrthosiphon pisum nymphs at temperatures between 15 and 35 °C. Logistic regression and Roger’s random predator models were employed to determine the type and parameters of the functional response. Harmonia axyridis larvae and adults exhibited Type II functional responses to A. pisum, and warming increased both the predation activity and host aphid control mortality. Female and 4th instar H. axyridis consumed the most aphids. For fourth instar larvae and female H. axyridis adults, the successful attack rates were 0.23 ± 0.014 h−1 and 0.25 ± 0.015 h−1; the handling times were 0.13 ± 0.005 h and 0.16 ± 0.004 h; and the estimated maximum predation rates were 181.28 ± 14.54 and 153.85 ± 4.06, respectively. These findings accentuate the high performance of 4th instar and female H. axyridis and the role of temperature in their efficiency. Further, we discussed such temperature-driven shifts in predation and prey mortality concerning prey-predator foraging interactions towards biological control.

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Understanding the Role of the LA in Functional Responses to Heart Failure

JACC Cardiovascular Imaging ◽

10.1016/j.jcmg.2016.10.006 ◽

2017 ◽

Vol 10 (10) ◽

pp. 1265-1267

Author(s):

Thomas H. Marwick ◽

David Kaye

Keyword(s):

Heart Failure ◽

Functional Responses

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Influence of Parenting Styles and Peer Attachment on Life Satisfaction Among Adolescents: Mediating Role of Self-Esteem

The Family Journal ◽

10.1177/10664807211009807 ◽

2021 ◽

pp. 106648072110098

Author(s):

Mudasir Aziz ◽

Waheeda Khan ◽

Faseeh Amin ◽

Mohammad Furqan Khan

Keyword(s):

Life Satisfaction ◽

Peer Relationships ◽

Parenting Styles ◽

Well Being ◽

Self Esteem ◽

Peer Attachment ◽

Equation Modeling ◽

Functional Responses ◽

The Relationship

Both parenting and peer relationship are essential in the formation of self-esteem among the adolescents which lead to overall psychological development. Life satisfaction is another outcome that describes the subjective well-being of any person and the quality of one’s life. Literature has already suggested the importance of parenting and peer relationships in the development of self-esteem which may lead to life satisfaction among adolescents. However, the relationship between three styles of parenting as well as peer attachment and life satisfaction mediated by self-esteem seems to be missing from the literature. This work is an important attempt toward fulfilling this research gap with respect to adolescents. The data were collected from 500 respondents which resulted in 412 functional responses. Structural equation modeling method was used to test the relationship in the study. The results revealed that both authoritative and permissive parenting have a positive influence on self-esteem in comparison to the negative influence of authoritarian parenting. Peer attachment also has an affirmative impact on self-esteem. Self-esteem also positively influences life satisfaction. Mediation results revealed that self-esteem partially mediates the association between three parenting styles, peer attachment, and life satisfaction. This study may offer unique insights to family counselors, couple counselors, and family educators about the role of different parenting styles and peer attachment with respect to the development of children’s self-esteem and life satisfaction. These results are also important for psychologists, sociologists, and other specialists with respect to understanding these factors for the well-being of adolescents.

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Distribution of seed dormancy classes across a fire-prone continent: effects of rainfall seasonality and temperature

Annals of Botany ◽

10.1093/aob/mcaa203 ◽

2020 ◽

Author(s):

Justin C Collette ◽

Mark K J Ooi

Keyword(s):

Seed Dormancy ◽

Critical Role ◽

Fire Regimes ◽

Common Species ◽

Functional Responses ◽

Stochastic Disturbance ◽

Climate Gradients ◽

Selective Pressures ◽

Rainfall Seasonality

Abstract Background and Aims Different seed dormancy classes control the timing of germination via different cues. The ecological dissimilarities between classes therefore suggest that they are likely to be subject to different selective pressures, and that species within each class will have diverse functional responses. We aimed to investigate this by assessing how variation in the distribution of dormancy classes is correlated with regional environmental factors, in particular rainfall seasonality and temperature. Additionally, we compare the relative proportions of species with physiological (PD) or physical (PY) dormancy to assess whether dormancy class influences their ability to persist under different rainfall seasonality regimes. Methods Dormancy class was assigned for 3990 species from 281 genera occurring across two climate regions, with either winter or aseasonal rainfall, across temperate fire-prone Australia. All regions have similar vegetation and fire regimes. Using a Bayesian framework, we compared the distribution of dormancy classes across temperature and rainfall climate gradients, for threatened and common species. Key Results A high dormant:non-dormant species ratio highlighted the critical role of dormancy across our study regions. Critically, species showing PD were more likely to be threatened in aseasonal rainfall climate regions. Conclusions Our results support the assumption that dormancy is favoured in environments with stochastic disturbance

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Role of Integrin αvβ3 in Vascular Biology

Thrombosis and Haemostasis ◽

10.1055/s-0037-1615250 ◽

1998 ◽

Vol 80 (11) ◽

pp. 726-734 ◽

Cited By ~ 115

Author(s):

Tatiana Byzova ◽

Ramin Rabbani ◽

Stanley D’Souza ◽

Edward Plow

Keyword(s):

Cell Biology ◽

Cell Function ◽

Thrombus Formation ◽

Cellular Adhesion ◽

Vascular Cells ◽

Functional Responses ◽

Adhesive Properties ◽

Adhesion Receptors ◽

Vascular Cell

IntroductionA defining characteristic of vascular cells is their adhesive status. The predominant cells of the blood vessel, endothelial cells (EC) and smooth muscle cells (SMC), are normally adherent but can be induced to migrate in response to vascular injury and angiogenic stimuli. The circulating blood cells are ordinarily nonadhesive but can rapidly acquire an adhesive phenotype in response to physiologic and pathophysiologic stimuli. As prime examples, platelets become adherent to the subendothelial matrix and to one another during thrombus formation, and leukocytes first adhere to EC and then transmigrate during the inflammatory response. At a molecular level, the adhesive properties of the vascular cells are determined by the adhesion receptors on their cell-surface and the functional state of these receptors. To match the variety of requisite cellular adhesive reactions, the repertoire of adhesion receptors expressed by vascular cells is broad. Multiple representatives of the immunoglobulin-like, the selectin, the cadherin and the integrin families of adhesion receptors are present on and have been implicated in the functions of the vascular cells. The importance of these adhesion receptors in vascular cell function is underscored by the severe pathogenetic consequences of their congenital deficiencies, such as in Glanzmann’s thrombasthenia, LAD (Leucocyte Adhesion deficiency) I and LAD II (1-3).The integrins are the largest and most broadly distributed of the families of cellular adhesion receptors. Of the integrins, αvβ3, originally identified as the vitronectin receptor, is particularly widely distributed. It is expressed at variable density on many types of vascular cells. Obviously, the adhesive properties of a cell are determined by its full repertoire of adhesion receptors. As an example, the adhesion of EC to fibrinogen/fibrin is mediated by no fewer than five receptors. Nevertheless, it is possible to dissect out the contributions of individual adhesion receptors, and αvβ3 has been implicated in many functional responses of vascular cells. This review focusses upon the role of αvβ3 in vascular cell biology. Other contributions of this multifunctional receptor, such as its role in neoplastic growth and invasion and in osteoclast-mediated bone resorption, are beyond the scope of this article and have been reviewed elsewhere (4, 5).

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Distinct phosphorylation sites in a prototypical GPCR differently orchestrate β-arrestin interaction, trafficking, and signaling

Science Advances ◽

10.1126/sciadv.abb8368 ◽

2020 ◽

Vol 6 (37) ◽

pp. eabb8368 ◽

Cited By ~ 1

Author(s):

Hemlata Dwivedi-Agnihotri ◽

Madhu Chaturvedi ◽

Mithu Baidya ◽

Tomasz Maciej Stepniewski ◽

Shubhi Pandey ◽

...

Keyword(s):

G Protein ◽

Phosphorylation Site ◽

Dynamics Simulation ◽

Phosphorylation Sites ◽

Functional Responses ◽

Biased Signaling ◽

The Stability ◽

G Protein Coupled ◽

Structural Aspects

Agonist-induced phosphorylation of G protein–coupled receptors (GPCRs) is a key determinant for their interaction with β-arrestins (βarrs) and subsequent functional responses. Therefore, it is important to decipher the contribution and interplay of different receptor phosphorylation sites in governing βarr interaction and functional outcomes. Here, we find that several phosphorylation sites in the human vasopressin receptor (V2R), positioned either individually or in clusters, differentially contribute to βarr recruitment, trafficking, and ERK1/2 activation. Even a single phosphorylation site in V2R, suitably positioned to cross-talk with a key residue in βarrs, has a decisive contribution in βarr recruitment, and its mutation results in strong G-protein bias. Molecular dynamics simulation provides mechanistic insights into the pivotal role of this key phosphorylation site in governing the stability of βarr interaction and regulating the interdomain rotation in βarrs. Our findings uncover important structural aspects to better understand the framework of GPCR-βarr interaction and biased signaling.

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Role of phosphoinositide 3-kinase β in platelet aggregation and thromboxane A2 generation mediated by Gi signalling pathways

Biochemical Journal ◽

10.1042/bj20100166 ◽

2010 ◽

Vol 429 (2) ◽

pp. 369-377 ◽

Cited By ~ 64

Author(s):

Analia Garcia ◽

Soochong Kim ◽

Kamala Bhavaraju ◽

Simone M. Schoenwaelder ◽

Satya P. Kunapuli

Keyword(s):

Platelet Aggregation ◽

Critical Role ◽

Thromboxane A2 ◽

Inhibitory Effect ◽

Human Platelets ◽

P2y12 Receptor ◽

Functional Responses ◽

Induce Platelet Aggregation ◽

Erk Phosphorylation

PI3Ks (phosphoinositide 3-kinases) play a critical role in platelet functional responses. PI3Ks are activated upon P2Y12 receptor stimulation and generate pro-aggregatory signals. P2Y12 receptor has been shown to play a key role in the platelet aggregation and thromboxane A2 generation caused by co-stimulation with Gq or Gz, or super-stimulation of Gi pathways. In the present study, we evaluated the role of specific PI3K isoforms α, β, γ and δ in platelet aggregation, thromboxane A2 generation and ERK (extracellular-signal-regulated kinase) activation. Our results show that loss of the PI3K signal impaired the ability of ADP to induce platelet aggregation, ERK phosphorylation and thromboxane A2 generation. We also show that Gq plus Gi- or Gi plus Gz-mediated platelet aggregation, ERK phosphorylation and thromboxane A2 generation in human platelets was inhibited by TGX-221, a PI3Kβ-selective inhibitor, but not by PIK75 (a PI3Kα inhibitor), AS252424 (a PI3Kγ inhibitor) or IC87114 (a PI3Kδ inhibitor). TGX-221 also showed a similar inhibitory effect on the Gi plus Gz-mediated platelet responses in platelets from P2Y1−/− mice. Finally, 2MeSADP (2-methyl-thio-ADP)-induced Akt phosphorylation was significantly inhibited in the presence of TGX-221, suggesting a critical role for PI3Kβ in Gi-mediated signalling. Taken together, our results demonstrate that PI3Kβ plays an important role in ADP-induced platelet aggregation. Moreover, PI3Kβ mediates ADP-induced thromboxane A2 generation by regulating ERK phosphorylation.

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Fyn and Lyn phosphorylate the Fc receptor γ chain downstream of glycoprotein VI in murine platelets, and Lyn regulates a novel feedback pathway

Blood ◽

10.1182/blood.v96.13.4246 ◽

2000 ◽

Vol 96 (13) ◽

pp. 4246-4253 ◽

Cited By ~ 107

Author(s):

Lynn S. Quek ◽

Jean-Max Pasquet ◽

Ingeborg Hers ◽

Richard Cornall ◽

Graham Knight ◽

...

Keyword(s):

Tyrosine Phosphorylation ◽

Fc Receptor ◽

Inhibitory Pathway ◽

Functional Responses ◽

Glycoprotein Vi ◽

Granule Secretion ◽

Activation Motif ◽

Additional Role ◽

Feedback Pathway

Abstract Activation of platelets by collagen is mediated by the complex glycoprotein VI (GPVI)/Fc receptor γ (FcRγ chain). In the current study, the role of 2 Src family kinases, Fyn and Lyn, in GPVI signaling has been examined using murine platelets deficient in one or both kinases. In the fyn−/−platelets, tyrosine phosphorylation of FcRγ chain, phopholipase C (PLC) activity, aggregation, and secretion are reduced, though the time of onset of response is unchanged. In the lyn−/−platelets, there is a delay of up to 30 seconds in the onset of tyrosine phosphorylation and functional responses, followed by recovery of phosphorylation and potentiation of aggregation and α-granule secretion. Tyrosine phosphorylation and aggregation in response to stimulation by collagen-related peptide is further attenuated and delayed in fyn−/−lyn−/−double-mutant platelets, and potentiation is not seen. This study provides the first genetic evidence that Fyn and Lyn mediate FcR immune receptor tyrosine-based activation motif phosphorylation and PLCγ2 activation after the ligation of GPVI. Lyn plays an additional role in inhibiting platelet activation through an uncharacterized inhibitory pathway.

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PDK1 selectively phosphorylates Thr(308) on Akt and contributes to human platelet functional responses

Thrombosis and Haemostasis ◽

10.1160/th13-06-0484 ◽

2014 ◽

Vol 111 (03) ◽

pp. 508-517 ◽

Cited By ~ 30

Author(s):

Carol Dangelmaier ◽

Bhanu Kanth Manne ◽

Elizabetta Liverani ◽

Jianguo Jin ◽

Paul Bray ◽

...

Keyword(s):

Protein Kinase ◽

Protein A ◽

Human Platelets ◽

Clot Retraction ◽

Functional Responses ◽

Atp Secretion ◽

Dependent Protein ◽

Induced Aggregation

Summary3-phosphoinositide-dependent protein kinase 1 (PDK1), a member of the protein A,G and C (AGC) family of proteins, is a Ser/Thr protein kinase that can phosphorylate and activate other protein kinases from the AGC family, including Akt at Thr308, all of which play important roles in mediating cellular responses. The functional role of PDK1 or the importance of phosphorylation of Akt on Thr308 for its activity has not been investigated in human platelets. In this study, we tested two pharmacological inhibitors of PDK1, BX795 and BX912, to assess the role of Thr308 phosphorylation on Akt. PAR4-induced phosphorylation of Akt on Thr308 was inhibited by BX795 without affecting phosphorylation of Akt on Ser473. The lack of Thr308 phosphorylation on Akt also led to the inhibition of PAR4-induced phosphorylation of two downstream substrates of Akt, viz. GSK3β and PRAS40. In vitro kinase activity of Akt was completely abolished if Thr308 on Akt was not phosphorylated. BX795 caused inhibition of 2-MeSADP-induced or collagen-induced aggregation, ATP secretion and thromboxane generation. Primary aggregation induced by 2-MeSADP was also inhibited in the presence of BX795. PDK1 inhibition also resulted in reduced clot retraction indicating its role in outside-in signalling. These results demonstrate that PDK1 selectively phosphorylates Thr308 on Akt thereby regulating its activity and plays a positive regulatory role in platelet physiological responses.

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Testing predator - prey theory by studying fluctuating populations of small mammals.

Wildlife Research ◽

10.1071/wr9950089 ◽

1995 ◽

Vol 22 (1) ◽

pp. 89 ◽

Cited By ~ 41

Author(s):

S. Boutin

Keyword(s):

Population Dynamics ◽

Small Mammals ◽

Limit Cycles ◽

Functional Responses ◽

Predator Satiation ◽

Linear Type ◽

Small Component ◽

Wide Range ◽

Fluctuating Populations

Fluctuating populations of small mammals provide an excellent opportunity to study the functional and numerical responses of predators because of the wide range in prey density that occurs. I reinterpret data from six studies that have examined the role of predation in the population dynamics of voles in California, southern Sweden and western Finland, of snowshoe hares in northern Canada, and of house mice and rabbits in Australia. Most studies have measured functional responses by relying on changes in diet as reflected by scat or stomach contents. These methods are probably biased toward showing predator satiation. Contrary to previous conclusions I find that there is little evidence for non-linear (Type 111) functional-response curves or predator satiation at high prey densities. Recent studies indicate that the functional and numerical responses of predators can be rapid and strong enough to initiate cyclic declines, dampen fluctuations, or even cause stable numbers. The exception to this appears to be the irruptions of mice and rabbits in Australia. I propose a general explanation for the role of predation whereby the effect of predation is largely dependent on the entire prey community. When potentially cyclic prey are a small component of the overall prey biomass, generalist predators are able to prevent fluctuations by strong functional or numerical responses. As the prey community becomes dominated by a few species that fluctuate, limit cycles predominate. Limit cycles turn into irruptive population dynamics when seasonal prey reproduction is eliminated because of extended periods of vegetation growth (vegetation flushes following drought). In the future we must test assumptions underlying the way we study predation by telemetric monitoring of prey mortality and by experimentally manipulating predation.

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