Effect of lipids on avian satellite cell proliferation, differentiation and heparan sulfate proteoglycan expression

The objective of this study was to determine the effects of fatty acids on the proliferation, differentiation, and expression of syndecan-4 and glypican-1 in avian myogenic satellite cells (SC). SC derived from the pectoralis major (PM) and biceps femoris (BF) muscles of the turkey and chicken were individually administered 8 different fatty acids in defined medium during proliferation. A parallel set of turkey SC was induced to differentiate. Highest levels of proliferation of turkey PM and BF SC occurred in cultures containing oleate. Linoleate and oleate were equipotent in supporting proliferation of chicken SC. Microscopic examination revealed that inclusion of docosahexaenoate or eicosapentaenoate was toxic towards both PM and BF SC from both species. Linolenate and arachidonate diminished levels of differentiation. Expression of glypican-1 varied between treatments to a greater extent with turkey BF than with PM SC. Expression in chicken PM and BF SC demonstrated a similar pattern in response to treatments. Turkey PM syndecan-4 expression varied between treatments, whereas expression in turkey BF SC was similar between treatments. Expression in chicken SC varied little between treatments. The results demonstrate species and muscle-specific differences in the parameters examined. It is proposed that changes in lipid raft receptor interactions may contribute to these observed differences.     

Interspecies chimera between primate embryonic stem cells and mouse embryos: monkey ESCs engraft into mouse embryos, but not post-implantation fetuses

Unequivocal evidence for pluripotency in which embryonic stem cells contribute to chimeric offspring has yet to be demonstrated in human or nonhuman primates (NHPs). Here, rhesus and baboons ESCs were investigated in interspecific mouse chimera generated by aggregation or blastocyst injection. Aggregation chimera produced mouse blastocysts with GFP-nhpESCs at the inner cell mass (ICM), and embryo transfers (ETs) generated dimly-fluorescencing abnormal fetuses. Direct injection of GFP-nhpESCs into blastocysts produced normal non-GFP-fluorescencing fetuses. Injected chimera showed >70% loss of GFP-nhpESCs after 21 h culture. Outgrowths of all chimeric blastocysts established distinct but separate mouse- and NHP-ESC colonies. Extensive endogenous autofluorescence compromised anti-GFP detection and PCR analysis did not detect nhpESCs in fetuses. NhpESCs localize to the ICM in chimera and generate pregnancies. Because primate ESCs do not engraft post-implantation, and also because endogenous autofluorescence results in misleading positive signals, interspecific chimera assays for pluripotency with primate stem cells is unreliable with the currently available ESCs. Testing primate ESCs reprogrammed into even more na?ve states in these inter-specific chimera assays will be an important future endeavor.     

Grooming coercion and the post-conflict trading of social services in wild Barbary macaques

In animal and human societies, social services such as protection from predators are often exchanged between group members. The tactics that individuals display to obtain a service depend on its value and on differences between individuals in their capacity to aggressively obtain it. Here we analysed the exchange of valuable social services (i.e. grooming and relationship repair) in the aftermath of a conflict, in wild Barbary macaques (Macaca sylvanus). The relationship repair function of post-conflict affiliation (i.e. reconciliation) was apparent in the victim but not in the aggressor. Conversely, we found evidence for grooming coercion by the aggressor; when the victim failed to give grooming soon after a conflict they received renewed aggression from the aggressor. We argue that post-conflict affiliation between former opponents can be better described as a trading of social services rather than coercion alone, as both animals obtain some benefits (i.e. grooming for the aggressor and relationship repair for the victim). Our study is the first to test the importance of social coercion in the aftermath of a conflict. Differences in competitive abilities can affect the exchange of services and the occurrence of social coercion in animal societies. This may also help explain the variance between populations and species in their social behaviour and conflict management strategies.     

Maternal lineages and Alzheimer disease risk in the Old Order Amish

Old Order Amish, founded by a small number of Swiss immigrants, exist in culturally isolated communities across rural North America. The consequences of genetic isolation and inbreeding within this group are evident by increased frequencies of many monogenic diseases and several complex disorders. Conversely, the prevalence of Alzheimer disease (AD), the most common form of dementia, is lower in the Amish than in the general American population. Since mitochondrial dysfunction has been proposed as an underlying cause of AD and a specific haplogroup was found to affect AD susceptibility in Caucasians, we investigated whether inherited mitochondrial haplogroups affect risk of developing AD dementia in Ohio and Indiana Amish communities. Ninety-five independent matrilines were observed across six large pedigrees and three small pedigrees then classified into seven major European haplogroups. Haplogroup T is the most frequent haplogroup represented overall in these maternal lines (35.4%) while observed in only 10.6% in outbred American and European populations. Furthermore, haplogroups J and K are less frequent (1.0%) than in the outbred data set (9.4–11.2%). Affected case matrilines and unaffected control lines were chosen from pedigrees to test whether specific haplogroups and their defining SNPs confer risk of AD. We did not observe frequency differences between AD cases compared to controls overall or when stratified by sex. Therefore, we suggest that the genetic effect responsible for AD dementia in the affected Amish pedigrees is unlikely to be of mitochondrial origin and may be caused by nuclear genetic factors.     

Expansion and functional relevance of high-avidity myelin-specific CD4+ T cells in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease in which myelin-specific T cells are believed to play a crucial pathogenic role. Nevertheless, so far it has been extremely difficult to demonstrate differences in T cell reactivity to myelin Ag between MS patients and controls. We believe that by using unphysiologically high Ag concentrations previous studies have missed a highly relevant aspect of autoimmune responses, i.e., T cells recognizing Ag with high functional avidity. Therefore, we focused on the characterization of high-avidity myelin-specific CD4+ T cells in a large cohort of MS patients and controls that was matched demographically and with respect to expression of MHC class II alleles. We demonstrated that their frequency is significantly higher in MS patients while the numbers of control T cells specific for influenza hemagglutinin are virtually identical between the two cohorts; that high-avidity T cells are enriched for previously in vivo-activated cells and are significantly skewed toward a proinflammatory phenotype. Moreover, the immunodominant epitopes that were most discriminatory between MS patients and controls differed from those described previously and were clearly biased toward epitopes with lower predicted binding affinities to HLA-DR molecules, pointing at the importance of thymic selection for the generation of the autoimmune T cell repertoire. Correlations between selected immunological parameters and magnetic resonance imaging markers indicate that the specificity and function of these cells influences phenotypic disease expression. These data have important implications for autoimmunity research and should be considered in the development of Ag-specific therapies in MS.     

Conserved linkage of two genes on the same macronuclear chromosome in spirotrichous ciliates

Macronuclear chromosomes of spirotrichous ciliates are mainly “nanochromosomes” containing only a single gene. We identified a two-gene chromosome in the spirotrich Sterkiella histriomuscorum (formerly Oxytricha trifallax) which, unlike other characterized two-gene molecules, contains reading frames oriented tail to tail. These are homologs of ribosomal protein L29 (RPL29) and cyclophilin. We found that both genes are transcribed, with their polyadenylation sites on opposite strands separated by only 135 bp. Furthermore, both genes in S. histriomuscorum are present only on one macronuclear chromosome and do not occur alone or linked to other genes. The corresponding micronuclear locus is fragmented into three nonscrambled gene segments (MDSs), separated by two noncoding segments (IESs). We also found that these two genes are linked on a macronuclear chromosome, similarly arranged tail to tail, in the three spirotrichs Stylonychia lemnae, Uroleptus sp., and Holosticha sp.. In addition, single-gene macronuclear chromosomes containing only the RPL29 gene were detected in the earlier diverged Holosticha and Uroleptus. These observations suggest a possible evolutionary trend towards loss of chromosomal breakage between these two genes. This study is the first to examine gene linkage in the macronucleus of several spirotrichs and may provide insight into the evolution of multi-gene macronuclear chromosomes and chromosomal fragmentation in spirotrichs. Electronic Supplementary Material Supplementary material is available for this article at     

Effects of glypican-1 on turkey skeletal muscle cell proliferation, differentiation and fibroblast growth factor 2 responsiveness

The heparan sulfate proteoglycan, glypican-1, is a low affinity receptor for fibroblast growth factor 2 (FGF2). Fibroblast growth factor 2 is a potent stimulator of skeletal muscle cell proliferation and an inhibitor of differentiation. Heparan sulfate proteoglycans like glypican-1 are required for FGF2 to transduce an intracellular signal. Understanding the role of glypican-1 in the regulation of FGF2-mediated signaling is important in furthering the understanding of the biological processes involved in muscle development and growth. In the current study, a turkey glypican-1 expression vector construct was transfected into turkey myogenic satellite cells resulting in the overexpression of glypican-1. The proliferation, differentiation, and responsiveness to FGF2 were measured in control and transfected cell cultures. The overexpression of glypican-1 in turkey myogenic satellite cells increased both satellite cell proliferation and FGF2 responsiveness, but decreased the rate of differentiation. The current data support glypican-1 modulation of both proliferation and differentiation through an FGF2-mediated pathway.     

Fibroblast growth factor 2 and protein kinase C alpha are involved in syndecan-4 cytoplasmic domain modulation of turkey myogenic satellite cell proliferation

Syndecan-4 core protein is composed of extracellular, transmembrane, and cytoplasmic domains. The cytoplasmic domain functions in transmitting signals into the cell through the protein kinase C alpha (PKCα) pathway. The glycosaminoglycan (GAG) and N-linked glycosylated (N-glycosylated) chains attached to the extracellular domain influence cell proliferation. The current study investigated the function of syndecan-4 cytoplasmic domain in combination with GAG and N-glycosylated chains in turkey muscle cell proliferation, differentiation, fibroblast growth factor 2 (FGF2) responsiveness, and PKCα membrane localization. Syndecan-4 or syndecan-4 without the cytoplasmic domain and with or without the GAG and N-glycosylated chains were transfected or co-transfected with a small interfering RNA targeting syndecan-4 cytoplasmic domain into turkey muscle satellite cells. The overexpression of syndecan-4 mutants increased cell proliferation but did not change differentiation. Syndecan-4 mutants had increased cellular responsiveness to FGF2 during proliferation. Syndecan-4 increased PKCα cell membrane localization, whereas the syndecan-4 mutants decreased PKCα cell membrane localization compared to syndecan-4. However, compared to the cells without transfection, syndecan-4 mutants increased cell membrane localization of PKCα. These data indicated that the syndecan‐4 cytoplasmic domain and the GAG and N-glycosylated chains are critical in syndecan-4 regulating satellite cell proliferation, responsiveness to FGF2, and PKCα cell membrane localization.     

Mom—It Helps When You're Right Here! Attenuation of Neural Stress Markers in Anxious Youths Whose Caregivers Are Present during fMRI

Close proximity to an attachment figure, such as a caregiver, has been shown to attenuate threat-related activity in limbic regions such as the hypothalamus in healthy individuals. We hypothesized that such features might be similarly attenuated by proximity during a potentially stressful situation in a clinically anxious population of youths. Confirmation of this hypothesis could support the role of attachment figures in the management of anxiety among children and adolescents. Three groups were analyzed: anxious children and adolescents who requested that their caregiver accompany them in the scanner room, anxious children and adolescents without their caregiver in the scanner room and healthy controls (each of N = 10). The groups were matched for age and, among the two anxious groups, for diagnosis (mean age 9.5). The children and adolescents were exposed to physical threat words during an fMRI assessment. Results indicate that activity in the hypothalamus, ventromedial, and ventrolateral prefrontal cortex were significantly reduced in anxious children and adolescents who requested that their caregiver accompany them in the scanner room compared to those without their caregiver in the scanner room. Mean activity in these regions in anxious children and adolescents with their caregiver in the scanner room was comparable to that of healthy controls. These data suggest links between social contact and neural mechanisms of emotional reactivity; specifically, presence of caregivers moderates the increase in anxiety seen with stressful stimuli. Capitalizing on the ability of anxious youths to manifest low levels of anxiety-like information processing in the presence of a caregiver could help in modeling adaptive function in behavioral treatments.     

Different development of myelin basic protein agonist- and antagonist-specific human TCR transgenic T cells in the thymus and periphery

Myelin basic protein (MBP)-specific T cells are thought to play a role in the development of multiple sclerosis. MBP residues 111-129 compose an immunodominant epitope cluster restricted by HLA-DRB1*0401. The sequence of residues 111-129 of MBP (MBP(111-129)) differs in humans (MBP122:Arg) and mice (MBP122:Lys) at aa 122. We previously found that approximately 50% of human MBP(111-129) (MBP122:Arg)-specific T cell clones, including MS2-3C8 can proliferate in response to mouse MBP(111-129) (MBP122:Lys). However, the other half of T cell clones, including HD4-1C2, cannot proliferate in response to MBP(111-129) (MBP122:Lys). We found that MBP(111-129) (MBP122:Lys) is an antagonist for HD4-1C2 TCR, therefore, MS2-3C8 and HD4-1C2 TCRs are agonist- and antagonist-specific TCRs in mice, respectively. Therefore, we examined the development of HD4-1C2 TCR and MS2-3C8 TCR transgenic (Tg) T cells in the thymus and periphery. We found that dual TCR expression exclusively facilitates the development of MBP(111-129) TCR Tg T cells in the periphery of HD4-1C2 TCR/HLA-DRB1*0401 Tg mice although it is not required for their development in the thymus. We also found that MS2-3C8 TCR Tg CD8(+) T cells develop along with MS2-3C8 TCR Tg CD4(+) T cells, and that dual TCR expression was crucial for the development of MS2-3C8 TCR Tg CD4(+) and CD8(+) T cells in the thymus and periphery, respectively. These results suggest that thymic and peripheral development of MBP-specific T cells are different; however, dual TCR expression can facilitate their development.