scholarly journals Biomineral armor in leaf-cutter ants

2020 ◽  
Author(s):  
Hongjie Li ◽  
Chang-Yu Sun ◽  
Yihang Fang ◽  
Caitlin M. Carlson ◽  
Huifang Xu ◽  
...  
Keyword(s):  
Protective Role ◽  
Nucleation And Growth ◽  
Anatomical Structures ◽  
Magnesium Calcite ◽  
Leaf Cutting ◽  
High Magnesium Calcite ◽  
Acromyrmex Echinatior

AbstractAlthough calcareous anatomical structures have evolved in diverse animal groups, such structures have been unknown in insects. Here, we report the discovery of high-magnesium calcite [CaMg(CO3)2] armor overlaying the exoskeletons of major workers of the leaf-cutter ant Acromyrmex echinatior. Live-rearing and in vitro synthesis experiments indicate that the biomineral layer accumulates rapidly as ant workers mature, that the layer is continuously distributed, covering nearly the entire integument, and that the ant epicuticle catalyzes biomineral nucleation and growth. In situ nanoindentation demonstrates that the biomineral layer significantly hardens the exoskeleton. Increased survival of ant workers with biomineralized exoskeletons during aggressive encounters with other ants and reduced infection by entomopathogenic fungi demonstrate the protective role of the biomineral layer. The discovery of biosynthesized high-magnesium calcite in the relatively well-studied leaf-cutting ants suggests that calcareous biominerals enriched in magnesium may be more common in metazoans than previously recognized.

scholarly journals Biomineral armor in leaf-cutter ants

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Hongjie Li ◽  
Chang-Yu Sun ◽  
Yihang Fang ◽  
Caitlin M. Carlson ◽  
Huifang Xu ◽  
...  
Keyword(s):  
Protective Role ◽  
In Vitro Synthesis ◽  
Anatomical Structures ◽  
Magnesium Calcite ◽  
Leaf Cutting ◽  
High Magnesium Calcite ◽  
Acromyrmex Echinatior

AbstractAlthough calcareous anatomical structures have evolved in diverse animal groups, such structures have been unknown in insects. Here, we report the discovery of high-magnesium calcite [CaMg(CO3)2] armor overlaying the exoskeletons of major workers of the leaf-cutter ant Acromyrmex echinatior. Live-rearing and in vitro synthesis experiments indicate that the biomineral layer accumulates rapidly as ant workers mature, that the layer is continuously distributed, covering nearly the entire integument, and that the ant epicuticle catalyzes biomineral nucleation and growth. In situ nanoindentation demonstrates that the biomineral layer significantly hardens the exoskeleton. Increased survival of ant workers with biomineralized exoskeletons during aggressive encounters with other ants and reduced infection by entomopathogenic fungi demonstrate the protective role of the biomineral layer. The discovery of biogenic high-magnesium calcite in the relatively well-studied leaf-cutting ants suggests that calcareous biominerals enriched in magnesium may be more common in metazoans than previously recognized.

Protective role of epithelium in the guinea pig airway

1989 ◽  
Vol 66 (4) ◽  
pp. 1547-1552 ◽  
Author(s):  
M. Munakata ◽  
I. Huang ◽  
W. Mitzner ◽  
H. Menkes
Keyword(s):  
Guinea Pig ◽  
Protective Role ◽  
Airway Epithelial ◽  
Serosal Side ◽  
Epithelial Surface ◽  
Airway Responses ◽  
Airway Tone ◽  
Stimulation Of

We developed an in vitro system to assess the role of the epithelium in regulating airway tone using the intact guinea pig trachea (J. Appl. Physiol. 64: 466–471, 1988). This method allows us to study the response of the airway when its inner epithelial surface or its outer serosal surface is stimulated independently. Using this system we evaluated how the presence of intact epithelium can affect pharmacological responsiveness. We first examined responses of tracheae with intact epithelium to histamine, acetylcholine, and hypertonic KCl when stimulated from the epithelial or serosal side. We then examined the effect of epithelial denudation on the responses to these agonists. With an intact epithelium, stimulation of the inner epithelial side always caused significantly smaller changes in diameter than stimulation of the outer serosal side. After mechanical denudation of the epithelium, these differences were almost completely abolished. In the absence of intact epithelium, the trachea was 35-fold more sensitive to histamine and 115-fold more sensitive to acetylcholine when these agents were applied to the inner epithelial side. In addition, the presence of an intact epithelium almost completely inhibited any response to epithelial side challenge with hypertonic KCl. These results indicate that the airway epithelial layer has a potent protective role in airway responses to luminal side stimuli, leading us to speculate that changes in airway reactivity measured in various conditions including asthma may result in part from changes in epithelial function.

Losartan Increases No Production from the Bovine Aortic Wall That is Stimulated by Angiotensin II

2003 ◽  
Vol 1 (3) ◽  
pp. 113-117 ◽  
Author(s):  
M. Myronidou ◽  
B. Kokkas ◽  
A. Kouyoumtzis ◽  
N. Gregoriadis ◽  
A. Lourbopoulos ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Aortic Wall ◽  
Vascular Wall ◽  
Protective Role ◽  
Normal Function ◽  
No Production ◽  
Chemical Inactivation

In these studies we investigated if losartan, an AT1- receptor blocker has any beneficial effect on NO production from the bovine aortic preparations in vitro while under stimulation from angiotensin II. Experiments were performed on intact specimens of bovine thoracic aorta, incubated in Dulbeco's MOD medium in a metabolic shaker for 24 hours under 95 % O2 and 5 % CO2 at a temperature of 37°C. We found that angiotensin II 1nM−10 μM does not exert any statistically significant action on NO production. On the contrary, angiotensin II 10nM increases the production of NO by 58.14 % (from 12.16 + 2.9 μm/l to 19.23 + 4.2 μm/l in the presence of losartan 1nM (P<0.05). Nitric oxide levels depend on both rate production and rate catabolism or chemical inactivation. Such an equilibrium is vital for the normal function of many systems including the cardiovascular one. The above results demonstrate that the blockade of AT1-receptors favors the biosynthesis of NO and indicate the protective role of losartan on the vascular wall.

scholarly journals Protocatechuic acids protects against high glucose- induced insulin resistance in human visceral adipose tissue

2016 ◽  
Vol 62 (5) ◽  
pp. 45-46
Author(s):  
Paulina Ormazabal ◽  
Beatrice Scazzocchio ◽  
Rosaria Varì ◽  
Annunziata Iacovelli ◽  
Roberta Masella
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Visceral Adipose Tissue ◽  
High Glucose ◽  
Protective Role ◽  
Insulin Sensitizer ◽  
20 Nm ◽  
Visceral Adipose

Adipocytes exposed to high glucose concentrations exhibit impaired insulin signaling. Binding of insulin to its membrane receptor activates insulin metabolic pathway leading to IRS-1 and AKT phosphorylations. The accumulation of visceral adipose tissue (VAT) correlates with insulin resistance and metabolic syndrome. Anthocyanins (ACN) are bioactive food compounds of great nutritional interest. We have shown that protocatechuic acid (PCA), a major metabolite of ACN, might exert insulin-sensitizer activities in human visceral adipose tissue. The aim of this work was to define the protective role of PCA against insulin-resistance induced by high glucose in VAT.Methodology: VAT obtained from control subject (BMI≤25) were separated in four experimental groups: i) PCA: samples treated for 24 h with 100 μM PCA, ii) GLU: VAT treated with 30 mM glucose for 24 h, iii) PCA+GLU: 1 hour incubation with 100 μM PCA before adding glucose (30 mM, 24 h), iv) CTR: vehicle. After treatment, VAT groups were (or not) acutely stimulated with insulin (20 nM, 20 min). Tyr-IRS-1 and Ser-Akt phosphorylations were assessed by Western blotting (WB) in basal or insulin stimulated tissues in all experimental groups. Samples were assessed for IRS-1, IR, Akt and GLUT4 protein content by WB. Results: No differences in protein contents between experimental groups were found. GLU tissues showed a lower increment in insulin-stimulated phosphorylation of IRS-1 and Akt compared to CTR and PCA samples. This impaired activation was completely reversed by the pretreatment with PCA.Conclusion: An in-vitro insulin-resistance condition induced by high glucose was established in biopsies of VAT. PCA restores the ability of GLU-tissues to fully respond to insulin by increasing IRS-1 and Akt phosphorylations. These results confirm the insulin-sensitizer effect of PCA on VAT previously reported by our group. An anthocyanin rich diet might help to protect against insulin-resistance in VAT.

The Role of Microbiology in Models of Dental Caries: Reaction Paper

1995 ◽  
Vol 9 (3) ◽  
pp. 255-269 ◽  
Author(s):  
G.H. Bowden
Keyword(s):  
Process Selection ◽  
Advantages And Disadvantages ◽  
Test Models ◽  
Plaque Development ◽  
In Vitro Systems ◽  
Selection Of

Models of the caries process have made significant contributions toward defining the roles of bacteria in caries. Microbiologists use a variety of in vitro systems to model aspects of the caries process. Also, in situ models in humans provide information on the microbiology of caries in vivo. These models do not involve the entire process leading to natural caries; consequently, the results from such studies are used to deduce the roles of bacteria in natural caries. Therefore, they can be described as Inferential Caries Models. In contrast, animal models and some clinical trials in humans involve natural caries and can be described as Complete Caries Models. Furthermore, these models are used in two distinct ways. They can be used as Exploratory Models to explore different aspects of the caries process, or as Test Models to determine the effects of anticaries agents. This dichotomy in approach to the use of caries models results in modification of the models to suit a particular role. For example, if we consider Exploratory Models, the in situ appliance in humans is superior to others for analyzing the microbiology of plaque development and demineralization in vivo. The chemostat and biofilm models are excellent for exploring factors influencing bacterial interactions. Both models can also be used as Test Models. The in situ model has been used to test the effects of fluoride on the microflora and demineralization, while the chemostat and biofilm models allow for the testing of antibacterial agents. Each model has its advantages and disadvantages and role in analysis of the caries process. Selection of the model depends on the scientific question posed and the limitations imposed by the conditions available for the study.

scholarly journals Extracellular Vesicles in Human Preterm Colostrum Inhibit Infection by Human Cytomegalovirus In Vitro

2020 ◽  
Vol 8 (7) ◽  
pp. 1087
Author(s):  
Manuela Donalisio ◽  
Simona Cirrincione ◽  
Massimo Rittà ◽  
Cristina Lamberti ◽  
Andrea Civra ◽  
...  
Keyword(s):  
Breast Milk ◽  
Extracellular Vesicles ◽  
Human Cytomegalovirus ◽  
Hcmv Infection ◽  
Protective Role ◽  
Surface Proteins ◽  
Human Colostrum ◽  
Clinical Illness

Breast milk is a complex biofluid that nourishes infants, supports their growth and protects them from diseases. However, at the same time, breastfeeding is a transmission route for human cytomegalovirus (HCMV), with preterm infants being at a great risk of congenital disease. The discrepancy between high HCMV transmission rates and the few reported cases of infants with severe clinical illness is likely due to the protective effect of breast milk. The aim of this study was to investigate the anti-HCMV activity of human preterm colostrum and clarify the role of colostrum-derived extracellular vesicles (EVs). Preterm colostrum samples were collected and the EVs were purified and characterized. The in vitro anti-HCMV activity of both colostrum and EVs was tested against HCMV, and the viral replication step inhibited by colostrum-purified EVs was examined. We investigated the putative role EV surface proteins play in impairing HCMV infection using shaving experiments and proteomic analysis. The obtained results confirmed the antiviral action of colostrum against HCMV and demonstrated a remarkable antiviral activity of colostrum-derived EVs. Furthermore, we demonstrated that EVs impair the attachment of HCMV to cells, with EV surface proteins playing a role in mediating this action. These findings contribute to clarifying the mechanisms that underlie the protective role of human colostrum against HCMV infection.

scholarly journals A Protective Role of Paeoniflorin in Fluctuant Hyperglycemia-Induced Vascular Endothelial Injuries through Antioxidative and Anti-Inflammatory Effects and Reduction of PKCβ1

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jing-Shang Wang ◽  
Ye Huang ◽  
Shuping Zhang ◽  
Hui-Jun Yin ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Protein Level ◽  
Umbilical Vein ◽  
Protective Role ◽  
Vascular Endothelial ◽  
Glucose Levels ◽  
Umbilical Vein Endothelial Cells

Hyperglycemia fluctuation is associated with diabetes mellitus (DM) complications when compared to persistent hyperglycemia. Previous studies have shown that paeoniflorin (PF), through its antiapoptosis, anti-inflammation, and antithrombotic properties, effectively protects against cardiovascular and cerebrovascular disease. However, the mechanism underlying the protection from PF against vascular injuries induced by hyperglycemia fluctuations remains poorly understood. Herein, we investigated the potential protective role of PF on human umbilical vein endothelial cells (HUVECs) subjected to intermittent glucose levels in vitro and in DM rats with fluctuating hyperglycemia in vivo. A remarkable increased apoptosis associated with elevated inflammation, increased oxidative stress, and high protein level of PKCβ1 was induced in HUVECs by intermittently changing glucose for 8 days, and PF recovered those detrimental changes. LY333531, a potent PKCβ1 inhibitor, and metformin manifested similar effects. Additionally, in DM rats with fluctuating hyperglycemia, PF protected against vascular damage as what has been observed in vitro. Taken together, PF attenuates the vascular injury induced by fluctuant hyperglycemia through oxidative stress inhibition, inflammatory reaction reduction, and PKCβ1 protein level repression, suggesting its perspective clinical usage.

scholarly journals HDAC2 attenuates airway inflammation by suppressing IL-17A production in HDM-challenged mice

2019 ◽  
Vol 316 (1) ◽  
pp. L269-L279 ◽  
Author(s):  
Tianwen Lai ◽  
Mindan Wu ◽  
Chao Zhang ◽  
Luanqing Che ◽  
Feng Xu ◽  
...  
Keyword(s):  
Airway Inflammation ◽  
Inflammatory Cytokines ◽  
Allergic Inflammation ◽  
Allergic Airway Inflammation ◽  
Inflammatory Cells ◽  
Protective Role ◽  
In Vivo Models

Histone deacetylase (HDAC)2 is expressed in airway epithelium and plays a pivotal role in inflammatory cells. However, the role of HDAC2 in allergic airway inflammation remains poorly understood. In the present study, we determined the role of HDAC2 in airway inflammation using in vivo models of house dust mite (HDM)-induced allergic inflammation and in vitro cultures of human bronchial epithelial (HBE) cells exposed to HDM, IL-17A, or both. We observed that HDM-challenged Hdac2+/− mice exhibited substantially enhanced infiltration of inflammatory cells. Higher levels of T helper 2 cytokines and IL-17A expression were found in lung tissues of HDM-challenged Hdac2+/− mice. Interestingly, IL-17A deletion or anti-IL-17A treatment reversed the enhanced airway inflammation induced by HDAC2 impairment. In vitro, HDM and IL-17A synergistically decreased HDAC2 expression in HBE cells. HDAC2 gene silencing further enhanced HDM- and/or IL-17A-induced inflammatory cytokines in HBE cells. HDAC2 overexpresion or blocking IL-17A gene expression restored the enhanced inflammatory cytokines. Collectively, these results support a protective role of HDAC2 in HDM-induced airway inflammation by suppressing IL-17A production and might suggest that activation of HDAC2 and/or inhibition of IL-17A production could prevent the development of allergic airway inflammation.

scholarly journals Selenium and vascular health

2011 ◽  
Vol 84 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Alan A. Sneddon
Keyword(s):  
Oxidative Damage ◽  
Protective Role ◽  
The Body ◽  
Vascular Health ◽  
Vascular Cells ◽  
Optimal Health ◽  
Oxidative Challenge ◽  
Se Status

Selenium (Se) is an important dietary micronutrient required for sustaining optimal health. Se is incorporated into proteins, many of which are antioxidants that protect the body against oxidative damage. As oxidative damage may contribute to the development of chronic diseases including cardiovascular disease (CVD), Se has been proposed to provide a protective role against this disease. Studies in vitro and in animals continue to provide increasing insight into the role of Se in promoting vascular health and ameliorating CVD. Se within vascular cells limits the adhesion together of such cells, an important early step in the development of vascular disease. Organic forms of Se may also afford vascular cells greater protection against oxidative challenge compared to inorganic forms. Nevertheless, current studies in humans investigating the relationship between Se and CVD have so far proved equivocal; larger randomized trials with different Se exposures in populations spanning the broad physiological Se status are needed to determine the criteria whereby Se may influence CVD outcome within different populations. Further studies are also needed to explore the effects of different Se species and the role of different selenoprotein genotypes in modifying Se status and their resultant impact on cardiovascular function.

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