scholarly journals Impact of Environmental Stressors on Gene Expression in the Embryo of the Italian Wall Lizard

2021 ◽  
Vol 11 (11) ◽  
pp. 4723
Author(s):  
Rosaria Scudiero ◽  
Chiara Maria Motta ◽  
Palma Simoniello
Keyword(s):  
Gene Expression ◽  
Protein Interactions ◽  
Membrane Trafficking ◽  
Translational Regulation ◽  
Cellular Protection ◽  
Terrestrial Vertebrate ◽  
Expression Of Genes ◽  
Stress Changes ◽  
Probable Consequence ◽  
The Impact

The cleidoic eggs of oviparous reptiles are protected from the external environment by membranes and a parchment shell permeable to water and dissolved molecules. As a consequence, not only physical but also chemical insults can reach the developing embryos, interfering with gene expression. This review provides information on the impact of the exposure to cadmium contamination or thermal stress on gene expression during the development of Italian wall lizards of the genus Podarcis. The results obtained by transcriptomic analysis, although not exhaustive, allowed to identify some stress-reactive genes and, consequently, the molecular pathways in which these genes are involved. Cadmium-responsive genes encode proteins involved in cellular protection, metabolism and proliferation, membrane trafficking, protein interactions, neuronal transmission and plasticity, immune response, and transcription regulatory factors. Cold stress changes the expression of genes involved in transcriptional/translational regulation and chromatin remodeling and inhibits the transcription of a histone methyltransferase with the probable consequence of modifying the epigenetic control of DNA. These findings provide transcriptome-level evidence of how terrestrial vertebrate embryos cope with stress, giving a key to use in population survival and environmental change studies. A better understanding of the genes contributing to stress tolerance in vertebrates would facilitate methodologies and applications aimed at improving resistance to unfavourable environments.

153 SUPPLEMENTATION WITH LINOLENIC ACID AND L-CARNITINE DURING IVM REDUCED THE EXPRESSION OF GENES RELATED TO LIPOGENESIS BUT DID NOT ALTER THE LIPID CONTENT AND CRYOTOLERANCE OF IN VITRO-PRODUCED EMBRYOS

2017 ◽  
Vol 29 (1) ◽  
pp. 185 ◽  
Author(s):  
B. C. S. Leao ◽  
N. A. S. Rocha Frigoni ◽  
P. C. Dall'Acqua ◽  
M. Ambrogi ◽  
G. B. Nunes ◽  
...  
Keyword(s):  
Gene Expression ◽  
Linolenic Acid ◽  
Lipid Content ◽  
Control Group ◽  
Intracellular Lipid ◽  
Chi Square ◽  
Sudan Black B ◽  
Expression Of Genes ◽  
The Impact

This study was conducted to evaluate the impact of supplementation during in vitro maturation (IVM) with linolenic acid (ALA), l-carnitine (L-car), or the combination of both supplements on the embryo intracellular lipid content and cryotolerance, as well as in the embryo expression of genes involved in lipid metabolism (lipogenesis regulation: SCD1, FASN, and SREBP1; and β-oxidation pathway: CPT1B and CPT2). Cumulus-oocyte complexes (n = 1076) were IVM for 22 h at 38.5°C and 5% CO2 in air, in TCM-199 medium with bicarbonate, hormones, and 10% FCS (control group), supplemented with 100 μM ALA (ALA group), 5 mM L-car (L-car group), or a combination of 100 μM ALA + 5 mM L-car (ALA + L-car group). After IVF, presumptive zygotes were in vitro cultured in SOFaa medium supplemented with 5 mg mL−1 BSA and 2.5% FCS, at 38.5°C and 5% CO2 in air during 7 days. Cleavage and blastocyst rates were evaluated on Day 3 and 7, respectively (IVF = Day 0). At Day 7, the blastocysts were stained with the lipophilic dye Sudan Black B (n = 60), vitrified/warmed (n = 260; Ingámed® protocol, Maringa-PR, Brazil), or collected for analysis of gene expression (n = 180). Embryonic development were analysed by ANOVA and the multiple comparisons of means were determined by Tukey’s test. The embryonic re-expansion data were subjected to chi-square test and the differences in gene expression among groups were evaluated by Duncan’s multiple range test (P < 0.05). Data are presented as means ± standard error means. There was no effect (P > 0.05) of the supplements used during IVM on cleavage (79.54 ± 2.76% to 82.16 ± 1.13%) and blastocyst rates (29.03 ± 3.07% to 30.46 ± 2.01%). Similarly, the intracellular lipid content in Day-7 blastocysts (1.03 ± 0.04 to 1.15 ± 0.07 pixels) and the embryonic cryotolerance, assessed by the re-expansion rates after 24 h (67.3 to 78.3%) hatching rates after 48 h (11.5 to 25.5%) of post-warming culture, were unaffected (P > 0.05) by the supplements of IVM medium. Although the treatments did not alter (P > 0.05) the expression of CPT1B and CPT2 genes, the expression of FASN gene was decreased (P < 0.05) in the ALA group and the expression of SREBP1 gene was decreased (P < 0.05) in the ALA and L-car groups. The expression of the gene SCD1 was reduced (P < 0.05) in all treatments compared with the control group. Thus, despite the lack of effects of the treatments performed during IVM on the intracellular lipid content and cryotolerance of the embryos derived from the treated oocytes, a reduction in the expression of genes related to lipogenesis was observed in Day-7 blastocysts. These results suggest that treatments performed in the oocytes during IVM may have prolonged effects, affecting the subsequent expression of genes in embryos. Further studies are needed to determine the mechanisms related to the differentiation of the oocyte machinery during maturation. Financial support was provided by FAPESP (#2012/10084–4 and #2013/07382–6).

scholarly journals Circulating miRNA 887 is differentially expressed in ARDS and modulates endothelial function

2020 ◽  
Vol 318 (6) ◽  
pp. L1261-L1269 ◽  
Author(s):  
Andrew J. Goodwin ◽  
Pengfei Li ◽  
Perry V. Halushka ◽  
James A. Cook ◽  
Aman S. Sumal ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Function ◽  
In Silico Analysis ◽  
Leukocyte Migration ◽  
Differentially Expressed ◽  
Expression Of Genes ◽  
Cell Gene Expression ◽  
And Function ◽  
The Impact

Circulating microRNAs (miRNAs) can be taken up by recipient cells and have been recently associated with the acute respiratory distress syndrome (ARDS). Their role in host predisposition to the syndrome is unknown. The objective of the study was to identify circulating miRNAs associated with the development of sepsis-related ARDS and examine their impact on endothelial cell gene expression and function. We determined miRNA levels in plasma collected from subjects during the first 24 h of admission to a tertiary intensive care unit for sepsis. A miRNA that was differentially expressed between subjects who did and did not develop ARDS was identified and was transfected into human pulmonary microvascular endothelial cells (HPMECs). RNA sequencing, in silico analysis, cytokine expression, and leukocyte migration assays were used to determine the impact of this miRNA on gene expression and cell function. In two cohorts, circulating miR-887-3p levels were elevated in septic patients who developed ARDS compared with those who did not. Transfection of miR-887-3p into HPMECs altered gene expression, including the upregulation of several genes previously associated with ARDS (e.g., CXCL10, CCL5, CX3CL1, VCAM1, CASP1, IL1B, IFNB, and TLR2), and activation of cellular pathways relevant to the response to infection. Functionally, miR-887-3p increased the endothelial release of chemokines and facilitated trans-endothelial leukocyte migration. Circulating miR-887-3p is associated with ARDS in critically ill patients with sepsis. In vitro, miR-887-3p regulates the expression of genes relevant to ARDS and neutrophil tracking. This miRNA may contribute to ARDS pathogenesis and could represent a novel therapeutic target.

Using muscle gene expression to estimate triacylglyceride deposition, and relative contributions of fatty acid synthesis and fatty acid import in intramuscular fat in cattle

2014 ◽  
Vol 54 (9) ◽  
pp. 1436 ◽  
Author(s):  
B. P. Dalrymple ◽  
B. Guo ◽  
G. H. Zhou ◽  
W. Zhang
Keyword(s):  
Gene Expression ◽  
Fatty Acid ◽  
De Novo ◽  
Acid Synthesis ◽  
Intramuscular Fat ◽  
Muscle Gene Expression ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Muscle Gene ◽  
The Impact

Intramuscular fat content (IMF%) in cattle influences the value of individual animals, especially for higher marbling markets. IMF is triacylglyceride (TAG) in lipid droplets in the intramuscular adipocytes. However, there are many different pathways from feed intake to the final common process of TAG synthesis and storage as IMF. To evaluate the relative importance of different pathways we compared changes in the expression of genes encoding proteins involved in the TAG and fatty acid (FA) synthesis pathways in the longissimus muscle of Piedmontese × Hereford (P×H) and Wagyu × Hereford (W×H) crosses. Based on these changes we have estimated the relative contributions of FA synthesised de novo in the intramuscular adipocyte and the uptake of circulating FA (both free and from TAG), from the diet or synthesised de novo in other tissues, to TAG deposition as IMF. We have analysed the impact of different developmental times and different diets on these processes. Increased de novo FA synthesis in intramuscular adipocytes appeared to contribute more than increased FA uptake from circulation to the additional TAG deposition in W×H compared with P×H cattle between 12 and 25 months (forage diet). Changing diet from forage to concentrate appeared to increase the importance of FA uptake from circulation relative to de novo FA synthesis for TAG synthesis in intramuscular adipocytes. These results are consistent with the literature based on analysis of lipid composition. Gene expression appears to provide a simple assay for identification of the source of FA for the deposition of IMF.

Transcriptomes reveal alterations in gravity impact circadian clocks and activate mechanotransduction pathways with adaptation through epigenetic change

2015 ◽  
Vol 47 (4) ◽  
pp. 113-128 ◽  
Author(s):  
Theresa Casey ◽  
Osman V. Patel ◽  
Karen Plaut
Keyword(s):  
Gene Expression ◽  
Late Pregnancy ◽  
Global Gene Expression ◽  
Circadian Clocks ◽  
Epigenetic Change ◽  
Pregnant Rats ◽  
Affymetrix Genechips ◽  
Expression Of Genes ◽  
The Impact

Few studies have investigated the impact of alterations in gravity on mammalian transcriptomes. Here, we describe the impact of spaceflight on mammary transcriptome of late pregnant rats and the effect of hypergravity exposure on mammary, liver, and adipose transcriptomes in late pregnancy and at the onset of lactation. RNA was isolated from mammary collected on pregnancy day 20 from rats exposed to spaceflight from days 11 to 20 of gestation. To measure the impact of hypergravity on mammary, liver, and adipose transcriptomes we isolated RNA from tissues collected on P20 and lactation day 1 from rats exposed to hypergravity beginning on pregnancy day 9. Gene expression was measured with Affymetrix GeneChips. Microarray analysis of variance revealed alterations in gravity affected the expression of genes that regulate circadian clocks and activate mechanotransduction pathways. Changes in these systems may explain global gene expression changes in immune response, metabolism, and cell proliferation. Expression of genes that modify chromatin structure and methylation was affected, suggesting adaptation to gravity alterations may proceed through epigenetic change. Altered gravity experiments offer insights into the role of forces omnipresent on Earth that shape genomes in heritable ways. Our study is the first to analyze the impact of alterations in gravity on transcriptomes of pregnant and lactating mammals. Findings provide insight into systems that sense gravity and the way in which they affect phenotype, as well as the possibility of sustaining life beyond Earth's orbit.

scholarly journals The Impact of Diet on Expression of Genes Involved in Innate Immunity in Goat Blood

2016 ◽  
Vol 8 (3) ◽  
pp. 1 ◽  
Author(s):  
Mulumebet Worku ◽  
Ahmed Abdalla ◽  
Sarah Adjei-Fremah ◽  
Hamid Ismail
Keyword(s):  
Gene Expression ◽  
Innate Immunity ◽  
Inflammatory Cytokines ◽  
Control Group ◽  
Colony Stimulating Factor ◽  
Sericea Lespedeza ◽  
Expression Of Genes ◽  
The Impact ◽  
Stimulating Factor ◽  
Pro Inflammatory Cytokines

<p>Sericea Lespedeza (SL), is a high-quality, low input forage that suppresses gastro-intestinal parasites in goats. The effect of dietary SL on the expression of genes involved in innate immunity in goats has not been established. The objective of this study was to evaluate the impact of a diet containing SL on the expression of genes involved in innate immunity in goat blood. Blood was collected by jugular venipuncture from goats fed a diet of 75% SL (n = 9) and a control group (n = 7), fed a SL free diet. Blood was used to evaluate expression of (CD-14, TLR-2, TLR-4, IL-10, IL-8, IL-2, INF-r, and TNF-a). Serum was extracted and used for evaluation of the secretion of pro-inflammatory cytokines (TNF-a, IFNr, granulocyte colony stimulating factor (GCSF), granulocyte-macrophage colony-stimulating factor (GMCSF), IL-1a, IL-8, IP-10 and RANTES) using a commercial ELISA kit. The level of gene expression of CD-14, TLR-2, TLR-4, IL-10, IL-8, IL-2, INF-r, and TNF-a was higher in treated animals compared to control. The <em>Sericea Lespedeza</em> diet affected the secretion of pro-inflammatory cytokines by increasing the serum levels of TNF-a, IFNr, GCSF, GMCSF, IL-1a, IP-10 (<em>P</em> &lt; 0.0002), and by decreasing (<em>P</em> &lt; 0.0001) IL-8 and RANTES in blood from goats fed SL. This suggests that dietary tannins modulate gene expression and may affect the goat's innate immune response in blood. Further research is needed to understand and harness the effect of dietary condensed tannins to modulate innate immunity in goats.</p>

scholarly journals Dysregulation of COVID-19 related gene expression in the COPD lung

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Alastair Watson ◽  
◽  
Lisa Öberg ◽  
Bastian Angermann ◽  
C. Mirella Spalluto ◽  
...  
Keyword(s):  
Gene Expression ◽  
Renin Angiotensin System ◽  
Chronic Obstructive ◽  
Angiotensin Ii Receptor ◽  
Ras Gene ◽  
Obstructive Pulmonary Disease ◽  
Expression Of Genes ◽  
Increased Risk ◽  
Bronchial Biopsies ◽  
The Impact

Abstract Background Chronic obstructive pulmonary disease (COPD) patients are at increased risk of poor outcome from Coronavirus disease (COVID-19). Early data suggest elevated Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) receptor angiotensin converting enzyme 2 (ACE2) expression, but relationships to disease phenotype and downstream regulators of inflammation in the Renin-Angiotensin system (RAS) are unknown. We aimed to determine the relationship between RAS gene expression relevant to SARS-CoV-2 infection in the lung with disease characteristics in COPD, and the regulation of newly identified SARS-CoV-2 receptors and spike-cleaving proteases, important for SARS-CoV-2 infection. Methods We quantified gene expression using RNA sequencing of epithelial brushings and bronchial biopsies from 31 COPD and 37 control subjects. Results ACE2 gene expression (log2-fold change (FC)) was increased in COPD compared to ex-smoking (HV-ES) controls in epithelial brushings (0.25, p = 0.042) and bronchial biopsies (0.23, p = 0.050), and correlated with worse lung function (r = − 0.28, p = 0.0090). ACE2 was further increased in frequent exacerbators compared to infrequent exacerbators (0.51, p = 0.00045) and associated with use of ACE inhibitors (ACEi) (0.50, p = 0.0034), having cardiovascular disease (0.23, p = 0.048) or hypertension (0.34, p = 0.0089), and inhaled corticosteroid use in COPD subjects in bronchial biopsies (0.33, p = 0.049). Angiotensin II receptor type (AGTR)1 and 2 expression was decreased in COPD bronchial biopsies compared to HV-ES controls with log2FC of –0.26 (p = 0.033) and − 0.40, (p = 0.0010), respectively. However, the AGTR1:2 ratio was increased in COPD subjects compared with HV-ES controls, log2FC of 0.57 (p = 0.0051). Basigin, a newly identified potential SARS-CoV-2 receptor was also upregulated in both brushes, log2FC of 0.17 (p = 0.0040), and bronchial biopsies, (log2FC of 0.18 (p = 0.017), in COPD vs HV-ES. Transmembrane protease, serine (TMPRSS)2 was not differentially regulated between control and COPD. However, various other spike-cleaving proteases were, including TMPRSS4 and Cathepsin B, in both epithelial brushes (log2FC of 0.25 (p = 0.0012) and log2FC of 0.56 (p = 5.49E−06), respectively) and bronchial biopsies (log2FC of 0.49 (p = 0.00021) and log2FC of 0.246 (p = 0.028), respectively). Conclusion This study identifies key differences in expression of genes related to susceptibility and aetiology of COVID-19 within the COPD lung. Further studies to understand the impact on clinical course of disease are now required.

scholarly journals The Impact of Hydrated Aluminosilicates Supplemented in Litter and Feed on Chicken Growth, Muscle Traits and Gene Expression in the Intestinal Mucosa

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2224
Author(s):  
Jakub Biesek ◽  
Aleksandra Dunisławska ◽  
Mirosław Banaszak ◽  
Maria Siwek ◽  
Marek Adamski
Keyword(s):  
Gene Expression ◽  
Body Weight ◽  
Intestinal Mucosa ◽  
Nutrient Sensing ◽  
Muscle Quality ◽  
Expression Of Genes ◽  
Group 3 ◽  
Group 2 ◽  
The Impact ◽  
Group 1

The aim of the study was to compare the production, muscle traits and gene expression in the intestinal mucosa of chickens supplemented with aluminosilicates in feed and litter simultaneously. A total of 300 Ross 308 were maintained for 42 days. Group 1 was the control group. In group 2, 0.650 kg/m2 of halloysite was added to the litter and 0.5–2% to the feed (halloysite and zeolite in a 1:1 ratio); in group 3, we added zeolite (0.650 kg/m2) to the litter and 0.5–2% to the feed. The production parameters, the slaughter yield and analyses of muscle quality were analyzed. There was a higher body weight, body weight gain and feed conversion ratio on day 18 and 33 in group 3, and a higher feed intake on day 19–33 in groups 2 and 3 than in 1. A lower water-holding capacity was found in the breasts of group 2 and in the legs of group 3 compared to group 1. The expression of genes related to the immune response, host defense and intestinal barrier and nutrient sensing in the intestinal tissue was analyzed. The results show a beneficial effect on the immune status of the host without an adverse effect on the expression of genes related to intestinal tightness or nutritional processes. Due to the growth, meat characteristics and the positive impact of immunostimulant and regulating properties, aluminosilicates can be suggested as a litter and feed additive in the rearing of chickens.

scholarly journals Slower development of lower canopy beans produces better coffee

2020 ◽  
Vol 71 (14) ◽  
pp. 4201-4214 ◽  
Author(s):  
Bing Cheng ◽  
Heather E Smyth ◽  
Agnelo Furtado ◽  
Robert J Henry
Keyword(s):  
Gene Expression ◽  
Metabolic Pathways ◽  
Global Gene Expression ◽  
Coffee Production ◽  
High Quality ◽  
Development Stages ◽  
Expression Of Genes ◽  
Coffee Beans ◽  
The Impact ◽  
Selection Of

Abstract The production of high-quality coffee is being challenged by changing climates in coffee-growing regions. The coffee beans from the upper and lower canopy at different development stages of the same plants were analyzed to investigate the impact of the microenvironment on gene expression and coffee quality. Compared with coffee beans from the upper canopy, lower canopy beans displayed more intense aroma with higher caffeine, trigonelline, and sucrose contents, associated with greater gene expression in the representative metabolic pathways. Global gene expression indicated a longer ripening in the lower canopy, resulting from higher expression of genes relating to growth inhibition and suppression of chlorophyll degradation during early bean ripening. Selection of genotypes or environments that enhance expression of the genes slowing bean development may produce higher quality coffee beans, allowing coffee production in a broader range of available future environments.

Impact of Trisomy 8 on Expression of Genes Located on Chromosome 8 in Different AML Subgroups.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2034-2034
Author(s):  
Claudia Schoch ◽  
Wolfgang Kern ◽  
Alexander Kohlmann ◽  
Martin Dugas ◽  
Wolfgang Hiddemann ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Dosage ◽  
Gene Expression Pattern ◽  
Chromosome 8 ◽  
Support Vector ◽  
Trisomy 8 ◽  
Gene Dosage Effect ◽  
Class Prediction ◽  
Expression Of Genes ◽  
The Impact

Abstract Trisomy 8 is the most frequently observed trisomy in acute myeloid leukemia (AML). It occurs as a sole karyotype abnormality or in addition to other chromosome aberrations. It was the aim of this study to analyze the impact of trisomy 8 on the expression of genes located on chromosome 8 in different AML subgroups. Therefore, gene expression analyses were performed in a total of 567 AML cases using Affymetrix U133A+B oligonucleotide microarrays. The following 14 subgroups were analyzed: +8 sole (n=19), +8 within a complex aberrant karyotype (n=11), +8 with t(15;17) (n=7), +8 and inv(16) (n=3), +8 with t(8;21) (n=3), +8 and 11q23/MLL (n=8), and +8 with other abnormalities (n=10). These were compared to 200 AML with normal karyotype and the following subgroups without trisomy 8: complex aberrant karyotype (n=73), t(15;17) (n=36), inv(16) (n=46), t(8;21) (n=37), 11q23/MLL (n=37), and other abnormalities (n=77). In total 1188 probe sets cover sequences located on chromosome 8 representing 580 genes. A significant higher mean expression of all genes located on chromosome 8 was observed in subgroups with +8 in comparison to their respective control groups (for all comparisons, p<0.05). Significantly higher expressed genes in groups with +8 in comparison to the respective groups without +8 were identified in all comparisons. The number of identified genes ranged from 40 in 11q23/MLL to 326 in trisomy 8 sole vs. normal. There was no common gene significantly overexpressed in all comparisons. Three genes (TRAM1, CHPPR, MGC40214) showed a significantly higher expression in 5 out of 7 comparisons. Between 19 and 107 genes with an exclusive overexpression in trisomy 8 cases in only one subtype comparison were identified. In addition, we performed class prediction using support vector machines (SVM) including all probe sets on the arrays. In one approach all 14 different subgroups were analyzed as one class each. Only 3 out of 61 cases with trisomy 8 were assigned into their correct subclass, while 40 cases were assigned to their corresponding genetic subclass without trisomy 8. In a second approach only two classes were defined: all cases with trisomy 8 combined vs. all cases without trisomy 8. Only 26 out of 61 (42.6%) with trisomy 8 were identified correctly underlining the fact that no distinct gene expression pattern is associated with trisomy 8 in general. Performing SVM only with genes located on chromosome 8 did not improve the correct assignment of cases with trisomy 8 overall. Only cases with trisomy 8 sole were correctly predicted in 58% as compared to 11% in SVM using all genes. In conclusion, overall the gain of chromosome 8 leads to a higher expression of genes located on chromosome 8. However, no consistent pattern of genes was identified which shows a higher expression in all AML subtypes with trisomy 8. This data suggest that the higher expression of genes located on chromosome 8 only in part is directly related to a gene dosage effect. Trisomy 8 may rather provide a platform for a higher expression of chromosome 8 genes which are specifically upregulated by accompanying genetic abnormalities in the respective AML subtypes. Therefore, trisomy 8 does not seem to be an abnormality determining specific disease characteristics such as the well known primary aberrations (t(8;21), inv(16), t(15;17), MLL/11q23) but rather a disease modulating secondary event in addition to primary cytogenetic or moleculargenetic aberrations.

scholarly journals Coordination of host and symbiont gene expression reveals a metabolic tug-of-war between aphids and Buchnera

2020 ◽  
Vol 117 (4) ◽  
pp. 2113-2121 ◽  
Author(s):  
Thomas E. Smith ◽  
Nancy A. Moran
Keyword(s):  
Gene Expression ◽  
Cell Growth ◽  
Membrane Trafficking ◽  
High Titer ◽  
Genotypic Variation ◽  
Essential Amino Acids ◽  
Eukaryotic Cell ◽  
Expression Of Genes ◽  
Elevated Expression ◽  
Aphid Clones

Symbioses between animals and microbes are often described as mutualistic, but are subject to tradeoffs that may manifest as shifts in host and symbiont metabolism, cellular processes, or symbiont density. In pea aphids, the bacterial symbiont Buchnera is confined to specialized aphid cells called bacteriocytes, where it produces essential amino acids needed by hosts. This relationship is dynamic; Buchnera titer varies within individual aphids and among different clonal aphid lineages, and is affected by environmental and host genetic factors. We examined how host genotypic variation relates to host and symbiont function among seven aphid clones differing in Buchnera titer. We found that bacteriocyte gene expression varies among individual aphids and among aphid clones, and that Buchnera gene expression changes in response. By comparing hosts with low and high Buchnera titer, we found that aphids and Buchnera oppositely regulate genes underlying amino acid biosynthesis and cell growth. In high-titer hosts, both bacteriocytes and symbionts show elevated expression of genes underlying energy metabolism. Several eukaryotic cell signaling pathways are differentially expressed in bacteriocytes of low- versus high-titer hosts: Cell-growth pathways are up-regulated in low-titer genotypes, while membrane trafficking, lysosomal processes, and mechanistic target of rapamycin (mTOR) and cytokine pathways are up-regulated in high-titer genotypes. Specific Buchnera functions are up-regulated within different bacteriocyte environments, with genes underlying flagellar body secretion and flagellar assembly overexpressed in low- and high-titer hosts, respectively. Overall, our results reveal allowances and demands made by both host and symbiont engaged in a metabolic “tug-of-war.”

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