Expression Of Individual Members Research Articles

Multispecies Analysis of Expression Pattern Diversification in the Recently Expanded Insect Ly6 Gene Family.

Gene families often consist of members with diverse expression domains reflecting their functions in a wide variety of tissues. However, how the expression of individual members, and thus their tissue-specific functions, diversified during the course of gene family expansion is not well understood. In this study, we approached this question through the analysis of the duplication history and transcriptional evolution of a rapidly expanding subfamily of insect Ly6 genes. We analyzed different insect genomes and identified seven Ly6 genes that have originated from a single ancestor through sequential duplication within the higher Diptera. We then determined how the original embryonic expression pattern of the founding gene diversified by characterizing its tissue-specific expression in the beetle Tribolium castaneum, the butterfly Bicyclus anynana, and the mosquito Anopheles stephensi and those of its duplicates in three higher dipteran species, representing various stages of the duplication history (Megaselia abdita, Ceratitis capitata, and Drosophila melanogaster). Our results revealed that frequent neofunctionalization episodes contributed to the increased expression breadth of this subfamily and that these events occurred after duplication and speciation events at comparable frequencies. In addition, at each duplication node, we consistently found asymmetric expression divergence. One paralog inherited most of the tissue-specificities of the founder gene, whereas the other paralog evolved drastically reduced expression domains. Our approach attests to the power of combining a well-established duplication history with a comprehensive coverage of representative species in acquiring unequivocal information about the dynamics of gene expression evolution in gene families.

Assessing gene network stability and individual variability in the fathead minnow (Pimephales promelas) transcriptome

Transcriptomics is increasingly used to assess biological responses to environmental stimuli and stressors such as aquatic pollutants. However, fundamental studies characterizing individual variability in mRNA levels are lacking, which currently limits the use of transcriptomics in environmental monitoring assessments. To address individual variability in transcript abundance, we performed a meta-analysis on 231 microarrays that were conducted in the fathead minnow (FHM), a widely used toxicological model. The mean variability for gene probes was ranked from most to least variable based upon the coefficient of variation. Transcripts that were the most variable in individual tissues included NADH dehydrogenase flavoprotein 1, GTPase IMAP family member 7-like and v-set domain-containing T-cell activation inhibitor 1-like while genes encoding ribosomal proteins (rpl24 and rpl36), basic transcription factor 3, and nascent polypeptide-associated complex alpha subunit were the least variable in individuals across a range of microarray experiments. Gene networks that showed high variability (based upon the variation in expression of individual members within the network) included cell proliferation, metabolism (steroid, lipids, and glucose), cell adhesion, vascularization, and regeneration while those that showed low variability (more stability) included mRNA and rRNA processing, regulation of translational fidelity, RNA splicing, and ribosome biogenesis. Real-time PCR was conducted on a subset of genes for comparison of variability collected from the microarrays. There was a significant positive relationship between the two methods when measuring individual variability, suggesting that variability detected in microarray data can be used to guide decisions on sample sizes for measuring transcripts in real-time PCR experiments. A power analysis revealed that measuring estrogen receptor ba (esrba) requires fewer biological replicates than that of estrogen receptor bb (esrbb) in the gonad and samples sizes required to detect a 50% change for reproductive-related transcripts is between 12 and 20. Characterizing individual variability at the molecular level will prove necessary as efforts are made toward integrating molecular tools into environmental risk assessments.

Evidence for differential expression of candida albicans virulence genes during oral infection in intact and human immunodeficiency virus type 1-transgenic mice.

To comprehensively assess the in vivo expression of Candida albicans hydrolytic enzyme genes during oropharyngeal candidiasis (OPC), a controlled sequential analysis of the temporal expression of individual members of the SAP (secretory aspartyl proteinase) gene family and PLB1 (phospholipase B) in a murine model of OPC was conducted. Acute infections in intact C3H and DBA/2 mice were terminated by clearance of C. albicans within 7 days after oral inoculation, but transgenic (Tg) mice expressing human immunodeficiency virus type 1 were persistently colonized until a final outgrowth before death. In contrast to the sustained expression of other SAP genes and PLB1, SAP7 and SAP8 were conspicuously distinguished by their transient expression in both intact and Tg mice. SAP5 and SAP9 were most strongly expressed throughout the course of infection in the Tg mice. These findings indicate that expression of individual members of the C. albicans SAP gene family is differentially regulated during experimental OPC.

The expression of pro- and anti-apoptosis Bcl-2 family proteins in lymphocytes from patients with multiple sclerosis

Programmed cell death (apoptosis) is critical for the normal development and homeostasis of the immune system. There is increasing evidence that dysregulations of apoptotic pathways are associated with autoimmune disease, including multiple sclerosis (MS). Cellular commitment to apoptosis is partly regulated by the Bcl-2 family proteins, which includes the death antagonists Bcl-2 and Bcl-X L, and death agonists Bax and Bad. Since the role of these proteins in the pathogenesis of MS is currently unknown, we analyzed their expression profile in peripheral and intrathecal lymphocytes from MS patients and appropriate controls. We observed a significant reduction in the expression ratios of pro-apoptotic to anti-apoptotic Bcl-2 members in both peripheral and intrathecal lymphocytes from MS patients when compared to corresponding ratios in patients with inflammatory or noninflammatory neurologic controls, or healthy individuals. The relative coexpression ratios of these pro- and anti-apoptotic Bcl-2 family proteins in MS were more significant than the expression of individual members. The low cellular expression ratios of pro-apoptotic proteins in MS were confirmed in vitro activated T lymphocytes. Cellular expression of Bcl-2, Bcl-X L, Bax or Bad in MS patients was independent of the expression of other apoptotic regulatory molecules, such as Fas receptor protein or FLIP. Our findings suggest that the abnormal expression patterns of Bcl-2 family proteins in MS may promote apoptotic resistance of potentially pathogenic, autoreactive lymphocytes, and may allow for continuing cellular proliferation and tissue destruction within the central nervous system.

Functional dissection of the insulin-like growth factor (IGF) svstem – prospects for animal breeding

Abstract. Growth is a biological phenomenon that is subject to complex endo-, para-, and autocrine control mechanisms. In addition to insulin, thyroid hormones, sex steroids, and growth hormone (GH), components of the IGF system have been identified as key players in growth regulation. However, since altered growth is often associated with multiple changes in this complex regulatory network, the specific effects of individual components remain to be determined. Therefore, our lab focused on the functional dissection of the IGF system using transgenic mice and other animal models which are characterized by altered expression of individual members of this system. Here we review some of our findings identifying members of the IGF family as candidate genes which may affect important traits in livestock production.

?-Ca2+/calmodulin-dependent protein kinase II expression pattern in adult mouse heart and cardiogenic differentiation of embryonic stem cells

delta-isoforms of the Ca(2+)/calmodulin-dependent protein kinase type II (CaMKII) are considered to substantially influence cardiac functions. However, no data exist on the expression of these isoforms in the mouse heart. We analyzed the transcript pattern of non-neuronally expressed delta-isoforms in heart and skeletal muscle of adult mice by RT-PCR. For members of the delta-CaMKII subclass with both variable domains (subclass II), weak transcriptional expression of isoforms delta(2) and delta(3) was found in the heart. In skeletal muscle no delta(3)-specific transcript was detectable. In cardiac tissue, stronger signals result from amplifications of delta(9) and from members of the subclass I lacking the second variable domain. Western blotting was performed using a subclass II-specific antibody. In murine cardiac and skeletal muscle tissue a delta-CaMKII protein pattern was obtained similar to that described for rat. To gain insight into the expression of delta-CaMKII during the earliest steps of cardiogenic differentiation, we analyzed the transcript pattern of murine embryonic stem cell-derived cardiomyocytes in various differentiation stages. Reproducible RT-PCR signals could be obtained for delta(6) and delta(10), both belonging to the delta-CaMKII subclass I. Transcripts for delta(6) were ubiquitously expressed, whereas transcripts for delta(10) were detectable in increasing amounts after 7-10 days of the onset of cardiogenic differentiation. Our results point to a differentiation-dependent expression of the two delta-CaMKII subclasses, and also to differences in the expression of individual members of subclass I during the early stages of cardiogenic differentiation.

Wild and cultivated barleys show differences in the expression pattern of a cold-regulated gene family under different light and temperature conditions.

Cold acclimation in plants involves the expression of many genes and gene families. The present study reports the expression analysis of three members of the blt14 gene family in barley. Gene-specific antisense oligonucleotides were used as probes in northern experiments so as to follow independently the expression of individual members of the gene family. Each clone revealed different accumulation kinetics when a spring and a winter cultivar were compared, suggesting that the different regulatory mechanisms leading to mRNA accumulation of an individual member of the blt14 gene family are genotype-dependent. In a collection of Hordeum spontaneum genotypes both qualitative and quantitative polymorphisms were found for the accumulation of blt14-related mRNAs, although no clear relationships were found between blt14 expression and frost resistance. The accumulation of the blt14-related mRNAs was also modulated by light and by the albino mutation a(n). The effects of light on the accumulation of the transcripts corresponding to the blt14 gene family were evaluated by comparing etiolated and green plants. Etiolated plants accumulate the blt14-related mRNAs at a detectable level already at 22 degrees C. When the same plants are exposed to cold in absence of light an increased mRNA accumulation above the level present in green cold-treated plants can be detected. On the contrary, etiolated plants showed a reduced blt14 accumulation when exposed to cold in the presence of light. Cold-induced expression of the blt14 gene family was strongly reduced in plants carrying the albino mutation a(n). This mutant showed a defective molecular response to cold even when probed with a cDNA coding for LEA type protein (paf93). The albino mutant a(n) was not able to harden when exposed to low temperature providing a direct evidence of the relationship between expression of cold-regulated (COR) genes and the development of cold hardening. Failure of cold acclimation in the mutant cannot be merely ascribed to the absence of photosynthetic activity, since etiolated wild-type plants accumulated COR mRNAs and improved frost resistance when exposed to cold.

The transcriptional regulatory strategy of the rat tissue kallikrein gene family

We have analysed the transcriptional regulatory strategy of the rat tissue kallikrein gene family, a strategy that provides universal submandibular gland expression of all family members coupled with otherwise disparate expression of individual members in a wide variety of organs. To test whether a locus control region (LCR) or individual gene enhancers control the family, the expression patterns of rat kallikrein genes were examined in transgenic mice bearing a series of rat genomic fragments spanning the kallikrein locus. Each fragment, present in recombinant P1 phage clones, contained two or three linked members of the rat family. Rat (r) genes KLK1, KLK2, KLK3, KLK7, KLK8, KLK9 and KLK10 on four different P1 clones were all correctly expressed at high levels in the submandibular glands of transgenic mice and in general showed the correct extra-salivary patterns characteristic of each family member. Moreover, when the neighbouring family members rKLK1 and rKLK3 were separated on non-overlapping fragments and tested in mice, each transgene was expressed correctly in the submandibular gland and in other organs characteristic of that gene. Thus the family locus is not controlled by an LCR; rather each gene appears to have an associated transcriptional enhancer that specifies high submandibular expression and contributes to the additional organ specificity of the family member.