ライフサイエンスコーパス: intragenic

1 ive motor, could also partially suppress the intragenic 3xAsp.

2 ene expression level-dependent enrichment of intragenic 5-hmC in mouse cerebellum and an age-dependen

3 Intragenic 5-methylcytosine and CTCF mediate opposing ef

4 key transcriptional regulators display high intragenic 5hmC levels in precursor cells at those devel

5 esults establish that proper coordination of intragenic alternative splicing is essential for normal

6 y elements that regulate the coordination of intragenic alternative splicing.

7 as diverse PAX5 alterations (rearrangements, intragenic amplifications or mutations); a second subtyp

8 tion of FCGR2B in B cells as possessing both intragenic and enhancer regulatory GWAS hits.

9 non-canonical translation products from both intragenic and extragenic genomic regions, including pep

10 t the majority of methylated CpG islands are intragenic and gene bodies are hypermethylated.

11 ombination breakpoints were partitioned into intragenic and intergenic events.

12 ive conditions an equal distribution between intragenic and intergenic locations was observed.

13 dentified associations between HU and 10 new intragenic and intergenic noncoding RNAs (ncRNAs), 2 of

14 se fibroblasts exit the nucleus with diverse intragenic and intergenic poly(A)-tail lengths.

15 f methylated CpG islands were shown to be in intragenic and intergenic regions, whereas less than 3%

16 ly distributed between intergenic, upstream, intragenic, and downstream of genes, with novel sites id

17 as a repressor of all transcription (genic, intragenic, and intergenic).

18 We further show that transcription from two intragenic antisense promoters strongly decreases the le

19 that Cdk9 inhibition or H2Bub1 loss induces intragenic antisense transcription of ~10% of fission ye

20 We discovered intragenic AR gene rearrangements in CRPC tissues, which

21 Large genomic rearrangements with intragenic breakpoints altering key regulatory genes inv

22 frequently observed in the absence of direct intragenic breakpoints, suggesting a requirement for sus

23 Homozygous deletions, intragenic breaks, or microdeletions were found in 33% o

24 factor) and the Cohesin complex occupy these intragenic chromatin boundaries.

25 d COLDWRAP are required to form a repressive intragenic chromatin loop at the FLC locus by vernalizat

26 also provide evidence for the presence of an intragenic chromatin loop between the two CTCF binding s

27 manner by complex networks of intergenic and intragenic cis-regulatory elements whose numbers and rep

28 in 85 unrelated individuals carrying an NF1 intragenic CNV.

29 e of two additional previously published NF1 intragenic CNVs.

30 be the predominant mechanisms leading to NF1 intragenic CNVs.

31 mal microarray were also applied to identify intragenic CNVs.

32 nsatory mutations in rpoA or rpoC, and a new intragenic compensatory substitution was identified.

33 ver, glutathione S-transferase pulldowns and intragenic complementation analysis of selected transpos

34 hermore, genetic bypass, protein fusion, and intragenic complementation assays define two distinct ad

35 at both SMN(A111G) and SMN from SMN2 undergo intragenic complementation in vivo to function in hetero

36 vection is the basis for several examples of intragenic complementation involving the enhancers of on

37 ere able, for the first time, to demonstrate intragenic complementation of replication-defective NS5A

38 ucleoprotein (snRNP) assembly, demonstrating intragenic complementation of SMN alleles.

39 otype resembling wild-type, but despite this intragenic complementation there are still changes in ho

40 hat can be separated genetically and undergo intragenic complementation.

41 tent, regions of alignment (exon, intron and intragenic), continuity of coverage, 3'/5' bias and coun

42 clinical specimens indicated that related AR intragenic copy number alterations occurred in CRPCa in

43 FLG also demonstrates intragenic copy number variation (CNV), with alleles enc

44 New research, however, shows that intragenic copy number variation within FLG also represe

45 n (aCGH) has revolutionized the detection of intragenic copy number variations.

46 Intragenic copy-number variants (CNVs) contribute to the

47 Intragenic CpG islands (iCGIs) and their corresponding h

48 lly methylated regions (TS-DMRs) observed at intragenic CpG islands and low CG density promoters.

49 We demonstrate that the intragenic CpG islands within the first intron of the hu

50 ificantly different in promoter CpG islands, intragenic CpG islands, gene bodies, and H3K36me3-enrich

51 We highlighted that altered intragenic CpG-methylation impairs multiple aspects of t

52 y, recent findings report that DNMT3B shapes intragenic CpG-methylation of highly-transcribed genes.

53 original-site mutation, gene conversion, and intragenic crossover.

54 The high percentage of intragenic CRP binding sites and our demonstration that

55 associated mechanisms exist to both suppress intragenic cryptic promoters during genic transcription

56 Rpd3S histone deacetylase complex to repress intragenic cryptic transcription.

57 stone H4 interaction is important to repress intragenic cryptic transcription.

58 ng the histone H4 interaction motif leads to intragenic cryptic transcripts, indicating that the Set2

59 ne and 5-carboxylcytosine are enriched at an intragenic CTCF-binding sites in the CD45 model gene and

60 These findings suggest that RNAPII pauses at intragenic CTCF-cohesin binding sites and that abrogatio

61 with pausing factors SPT5 and NELF-A, at the intragenic CTCF-cohesin binding sites.

62 ne clinical diagnostic testing identified an intragenic de novo deletion of TRIO in a boy with ID.

63 We report the first intragenic deletion and frameshift mutations identified

64 .1008dupT (p.Asp337*) nonsense variant or an intragenic deletion encompassing AARS2 exons 5-7.

65 Gene rearrangement in the form of an intragenic deletion is the primary mechanism of oncogeni

66 This intragenic deletion marked a specific CWR-R1 cell popula

67 egion flanking the deletion unveiled a large intragenic deletion of 4,165 nucleotides.

68 PDGFRA intragenic deletion of exons 8 and 9 were previously sho

69 Here we report that intragenic deletion of the dystrophin-encoding and muscu

70 e results indicate that gene duplication and intragenic deletion played essential roles in the origin

71 identified de novo mutations, including one intragenic deletion probably disrupting normal splicing

72 gene, and six cases of PDGFRA(Delta8, 9), an intragenic deletion rearrangement.

73 mutations, four amino acid substitutions, an intragenic deletion, and a 4.7-Mb multigene deletion inv

74 plication-triplication re-arrangement and an intragenic deletion, predicted to result in altered tran

75 ere detected, including one homozygous BRCA1 intragenic deletion.

76 ght-year-old boy (A-II) with a de novo FOXP2 intragenic deletion.

77 pping and copy number analysis we identified intragenic deletions and mutations in OCLN in nine patie

78 xpected to change as previously unrecognized intragenic deletions are uncovered.

79 and careful review process, aCGH can uncover intragenic deletions as small as dozen bases.

80 mapping analysis for 62 clinical cases with intragenic deletions in the human DMD gene (50 cases) an

81 inactivating somatic mutations and frequent intragenic deletions of PARK2 in human malignancies.

82 We identified recurrent intragenic deletions of PAX5 or VPREB1 in constellation

83 thermore, we identified a series of stepwise intragenic deletions that occurred at different times in

84 to uncover the true detection size limit of intragenic deletions with this technology.

85 Our findings highlight the role of intragenic DNA methylation and DNA binding protein BORIS

86 pre-mRNA "splicing code" to include dynamic intragenic DNA methylation catalyzed by the TET proteins

87 The exact role of intragenic DNA methylation in regulating tissue-specific

88 s relatively well characterized, the role of intragenic DNA methylation remains unclear.

89 Here we report that the intragenic DNA methylation-mediated binding of Brother o

90 nding sites and our demonstration that these intragenic DNA sequences significantly contribute to bio

91 This permissive intragenic domain is constrained by sharp chromatin boun

92 The combination of this large intragenic duplication and 5T/12TG is the probable cause

93 s of multidomain inhibitors which evolved by intragenic duplication and are released by processing (e

94 to have evolved through sequential rounds of intragenic duplication from a primordial one-domain prec

95 ludes exons 1-5 of Elmod1, and rda(2J) is an intragenic duplication of exons 3-8 of Elmod1.

96 Intragenic duplications of the portion of FGFR1 encoding

97 the functional importance of this conserved intragenic element in the regulation of alternative spli

98 inates a three-dimensional stricture between intragenic elements of CFTR bound by several cell-type s

99 sed definition of enhancer elements revealed intragenic enhancer methylation as a mechanism for high-

100 that expresses LacZ under the control of an intragenic enhancer of Dlx5 and Dlx6 (Dlx5/6-LacZ).

101 ely with nascent eRNA expression, the act of intragenic enhancer transcription alone, but not eRNAs,

102 ons, we demonstrate a physiological role for intragenic enhancer-mediated transcription attenuation i

103 E-box-GATA-ETS composite element of a Gata2 intragenic enhancer.

104 ependent activity and an ESC-specific distal intragenic enhancer; the latter is rapidly downregulated

105 Intergenic and intragenic enhancers found inside topologically associat

106 Here we show that activated, intragenic enhancers frequently act as alternative tissu

107 Here we show that transcription at intragenic enhancers interferes with and attenuates host

108 We propose that intragenic enhancers not only enhance transcription of o

109 n deficiency upon glucose deprivation causes intragenic enrichment of acetylated histone H3 at lysine

110 We conclude that high-throughput mapping of intragenic epistasis can identify key structural and fun

111 he fitness landscape, but a clear picture of intragenic epistasis has yet to emerge.

112 uantitative description of pairwise/tertiary intragenic epistasis involving adaptive mutations.

113 urther reveal the prevalence and patterns of intragenic epistasis, we present a survey of epistatic i

114 o systematically survey a model landscape of intragenic epistasis, we quantified the fitness of ~60,0

115 explicitly modeling non-dosage dependent and intragenic epistatic effects when predicting expression.

116 he identification and characterization of an intragenic epistatic interaction between the attenuating

117 positions outside of CpG islands and within intragenic (exon) regions of the zebrafish genome.

118 nt of H3K36 methylation with H3K27me3 at the intragenic FLC nucleation site during the cold.

119 chromatin environment, resulted in increased intragenic FLO8 transcripts.

120 te thermal stress, HSP genes undergo intense intragenic folding interactions that go well beyond 5'-3

121 he mechanisms still poorly understood of the intragenic function of DNMT3B and DNA methylation in gen

122 supervised fusion transcripts, detection of intragenic fusion variants, homology scores and fusion f

123 ydrolysis and Pi release, and the effects of intragenic G31R suppressors on these reactions, and on t

124 stador') plants engineered to overexpress an intragenic gain-of-function allele of the type I proton

125 gene fusions, and finally via activation by intragenic gain-of-function mutations.

126 To date, only two clinically relevant intragenic genotype-phenotype correlations have been rep

127 cts preferentially associate with changes of intragenic H3K4me3 and at lesser extent of H3K27me3 and

128 Depletion of KDM5B or MRG15 increases intragenic H3K4me3, increases cryptic intragenic transcr

129 Certain intragenic highly conserved elements have been associate

130 e sequencing (WES) data to identify rare and intragenic homozygous and hemizygous (HMZ) deletions tha

131 ylation valleys; however, IMs generally lack intragenic hypomethylation signatures of advanced malign

132 f H-NS-suppressed transcripts in E. coli are intragenic in origin.

133 probably disrupting normal splicing and one intragenic insertion that results in a frameshift and pr

134 warfism conferred by Rht-B1c is caused by an intragenic insertion, which results in an in-frame 90-bp

135 We find that intragenic levels of the polycomb mark H3K27me3 anti-cor

136 iseases with early mortality and demonstrate intragenic localized patterns of variants that suggest p

137 Hydroxymethylation at both promoter and intragenic locations correlated positively with gene exp

138 ricted target genes are at distal inter- and intragenic locations.

139 es to analyze WBC DNA methylation of two ATM intragenic loci (ATMmvp2a and ATMmvp2b) and genome-wide

140 We discovered a novel intragenic long noncoding RNA (lncRNA) within the IGF1R

141 In leaves, an intragenic loop is formed, blocking HaWRKY6 transcriptio

142 We found that formation of this intragenic loop preferentially enhances ANG transcriptio

143 which mediates transcription termination and intragenic looping at eukaryotic genes.

144 issue of Science, Tan-Wong et al. find that intragenic looping increases the proper orientation of R

145 a target of deletion in GBM, often via focal intragenic loss.

146 Differential burden with intragenic low-frequency variants reveals putatively cau

147 ation initiation, often requires splicing of intragenic material.

148 full-segment 2q23.1 deletions and those with intragenic MBD5 rearrangements, including alterations co

149 rating the antiquity of associations between intragenic methylation and gene expression.

150 s of neuronal gene inheriting high levels of intragenic methylation from the mother and maintaining t

151 These results support a major role for intragenic methylation in regulating cell context-specif

152 methylation is inversely correlated whereas intragenic methylation is directly correlated with gene

153 Consistent with previous work we found that intragenic methylation is positively correlated with gen

154 Tissue-specific intragenic methylation might reduce, or, paradoxically,

155 To investigate the role of intragenic methylation, we generated a map of DNA methyl

156 cancer cell lines, we identified homozygous intragenic microdeletions involving genes encoding compo

157 Importantly, intragenic microdeletions of the EGFR phosphatase PTPRS

158 Searching specifically for small intragenic microdeletions using high-resolution genomic

159 Intragenic microdeletions, balanced structural rearrange

160 Here, we show that miR-483-5p, an intragenic microRNA of the imprinted IGF2, regulates MeC

161 -exon boundaries, alternative promoters, and intragenic microRNAs.

162 Intragenic miRNAs account for approximately 50% of mamma

163 e show that evolutionarily conserved ('old') intragenic miRNAs tend to be coexpressed with host genes

164 As dominate in human genome, the majority of intragenic miRNAs that show coexpression with host genes

165 ed in this study-deep intronic mutations and intragenic modifiers-might represent more generalizable

166 bundles suggests that the proteins arose by intragenic multiplication.

167 uggests that the proteins may have arisen by intragenic multiplication.

168 The reported alleles having an intragenic mutation could not be causally associated wit

169 ccRCC), the most common type, begins with an intragenic mutation in the von Hippel-Lindau (VHL) gene

170 tional cooperating genetic events, including intragenic mutations and copy number alterations, are re

171 The dinB intragenic mutations examined were either base pair subs

172 proach enables the identification of smaller intragenic mutations including single-nucleotide variant

173 Results Five patients were identified with intragenic mutations predicted to restore BRCA1/2 open r

174 These intragenic mutations suppress all of the evaluated isp-1

175 at status, TS expression levels reported, TS intragenic mutations, and TP53 status in outbred and exp

176 ve revealed ~140 genes that, when altered by intragenic mutations, can promote or "drive" tumorigenes

177 o promoter hypermethylation or other somatic intragenic mutations.

178 ant firing of replication origins to explain intragenic nonrecurrent rearrangements within genes, inc

179 ly significant increase in the proportion of intragenic novel L1s in DLPFC of PDS.

180 re we identify a single point mutation at an intragenic nucleation site within FLC that prevents this

181 Loss of chdC caused an increase of intragenic nucleosome spacing and misregulation of gene

182 neage-specific pattern of expression and are intragenic or adjacent to TH lineage-specific genes enco

183 Six intragenic ouf suppressors with near wild-type (WT) JA p

184 plification (MLPA) showed the presence of an intragenic paternally derived duplication involving exon

185 asons thought to involve differences both in intragenic Pkd1 mutations and in modifier alleles.

186 y well-known cases, breakpoints occur at two intragenic positions, leading to in-frame gene-gene fusi

187 is tissue-specific DNA methylation regulates intragenic promoter activity in vitro and in vivo.

188 ibed by RNA polymerase III (Pol III) from an intragenic promoter at levels similar to that of the cap

189 trols UBI4 by inducing transcription from an intragenic promoter, and the resulting truncated mRNA en

190 richia coli ehxCABD operon contains numerous intragenic promoters in both sense and antisense orienta

191 allow transcription initiation from cryptic intragenic promoters.

192 t, enhancer RNAs and to be more prominent in intragenic, rather than intergenic, enhancers.

193 orms in 22Rv1 CRPCa cells is associated with intragenic rearrangement of an approximately 35-kb AR ge

194 rons 1, 2, 3, and 50 were also identified as intragenic-rearrangement hotspots within NF1.

195 r, these data provide the first report of AR intragenic rearrangements in CRPCa and an association wi

196 ted by flanking low-copy repeats (LCRs), NF1 intragenic rearrangements vary in size, location, and re

197 ix-loop-helix family transcription factor by intragenic recombinants and provided unambiguous evidenc

198 in-frame sequence duplications, whereas most intragenic recombinants were homologous.

199 e bz gene were performed and more than 2,500 intragenic recombinants were scored.

200 Next, we examined intragenic recombination among the core genes and found

201 ea mays) NLR protein Rp1-D21 derives from an intragenic recombination between two NLRs, Rp1-D and Rp1

202 We are interested in how intragenic recombination contributes to the evolution of

203 quence polymorphisms affect the frequency of intragenic recombination events (gene conversions).

204 However, significant associations between intragenic recombination events and variation in gene ex

205 This kept the overall number of intragenic recombination events nearly invariable in a g

206 However, intragenic recombination events not associated with flan

207 Intragenic recombination explores a unique subset of seq

208 ere observed, suggesting potential roles for intragenic recombination in plant phenotypic diversity.

209 Intragenic recombination is active in these introns, as

210 expected by random chance alone, and neither intragenic recombination nor increased mutability can ex

211 h other amongst the progeny having undergone intragenic recombination.

212 duplicated, the loxPint module serves as an intragenic recombineering point that can be used for the

213 ed with former and non-smokers, including an intragenic region of the aryl hydrocarbon receptor repre

214 CDKN2A/B, EXT2, FTO, HHEX-IDE, IGF2BP2, the intragenic region on 11p12, JAZF1, KCNQ1, LOC387761, MTN

215 is particularly enriched at promoters and in intragenic regions (gene bodies) but is largely absent f

216 t promoters but also retention at inter- and intragenic regions and repetitive elements.

217 eals that KDM5B is predominantly targeted to intragenic regions and that it is recruited to H3K36me3

218 g of 5hmC revealed its specific reduction on intragenic regions from both GDM and preeclampsia compar

219 ranscription from cryptic start sites within intragenic regions of actively transcribed genes.

220 mitigating RNA polymerase II progression in intragenic regions of actively transcribed genes.

221 onic fibroblasts (MEFs) and is restricted to intragenic regions of actively transcribing genes by EHM

222 ly regulates histone H3K4 methylation within intragenic regions of its target genes.

223 demonstrate the recognition of promoter and intragenic regions of multiple mmpL genes by these prote

224 ting RNAPII colocalize extensively along the intragenic regions of TGFbeta target genes.

225 locus sequence typing (TLST) scheme based on intragenic regions of two antigenic genes, ace and salA

226 In the intergenic and intragenic regions on the X chromosome, the sites outsid

227 ncRNAs can be transcribed from intergenic or intragenic regions or from introns of protein-coding gen

228 recruitment of the NF-kappaB factor RELA to intragenic regions regulates alternative splicing upon N

229 a samples showed differential methylation of intragenic regions that strongly correlated with express

230 " GASs were re-annotated to the promoters or intragenic regions using Ensembl, UCSC and AceView gene

231 d histone acetylation that were localized to intragenic regions, enriched for Myc DNA binding motifs,

232 od (ISS), which predicts phased sequences of intragenic regions, using SNPs.

233 t6 both contribute to restricting H2A.Z from intragenic regions.

234 -specific EKLF occupancy is predominantly in intragenic regions.

235 including enrichment of 5fC in enhancer and intragenic regions.

236 ve regulation events (FGFR2 enhancer in BCC, intragenic regulation of FOXP1 in SCC, and WNT5A promote

237 by RegulationSpotter to account for possible intragenic regulatory effects.

238 We conclude that fast-evolving intragenic repeat expansions can fundamentally change th

239 We show significant hypermethylation of one intragenic repetitive element in breast cancer cases com

240 ong-range interaction occurring between this intragenic response element and the transcription start

241 However, secondary intragenic (reversion) mutations that restore protein fu

242 We performed an intragenic screen for suppressors of lethality induced b

243 g the elongation phase of protein synthesis, intragenic SD-like sequences stimulate ribosome frameshi

244 ought here to induce the excision of a large intragenic segment within the intact dystrophin gene loc

245 eshifting in the RF2 gene (prfB) involves an intragenic Shine-Dalgarno (SD) sequence.

246 An intragenic single nucleotide polymorphism and an extrage

247 ary, we present an algorithm to detect rare, intragenic, single-exon deletion CNVs using WES data; th

248 c Polycomb complexes/H3K27me3 at a localized intragenic site during the cold.

249 es were significantly enriched among 103,466 intragenic sites (P(hypergeometric) = 0.006; P(permutati

250 genes were significantly enriched among all intragenic sites that achieved a p < 0.05 throughout the

251 iting-out of RUNX1 enhancer (eR1) within its intragenic super-enhancer, or BET protein BRD4 depletion

252 Further characterization of the intragenic suppressive mutations located in the RRS1-R T

253 An intragenic suppressor introducing a positive charge rest

254 tein encoded by the previously characterized intragenic suppressor mutant log1-1, with an arginine in

255 We isolated a spontaneous intragenic suppressor mutant of the priA beta-hairpin de

256 The evidence is based on results from an intragenic suppressor mutation screen and domain swappin

257 Together with an intragenic suppressor mutation that mimics benzamide bin

258 defect in MurJ biogenesis; by engineering an intragenic suppressor mutation that restores MurJ biogen

259 sms regulating CheZ activity, we isolated 10 intragenic suppressor mutations of cheZ21IT that restore

260 itution mutations, and spontaneously arising intragenic suppressor mutations on intracellular replica

261 ting cells with small molecule correctors or intragenic suppressor mutations.

262 We isolated an intragenic suppressor of atprmt3-2, which rescues the de

263 nt substitution, A375V, was identified as an intragenic suppressor of D103V, a negative mutant enzyme

264 We selected for intragenic suppressors of dnaN5 that rescued viability a

265 We isolated three intragenic suppressors of dnaN5 that restored growth at

266 Second-site intragenic suppressors of E467A isolated within the SBD

267 ctions in FtsA function in vivo, we isolated intragenic suppressors of ftsA27.

268 sis screen, we were then able to identify 11 intragenic suppressors of hmp-1(fe4) that revert actin b

269 biochemical approaches, we characterized the intragenic suppressors of sensitive to low humidity 1 (s

270 Analysis of intragenic suppressors of this mutant suggests it has di

271 hat inactivate AmtB and here characterize 38 intragenic suppressors upstream of the C terminus ( appr

272 Here we report a series of intragenic suppressors, all located within a highly cons

273 g in CRPCa 22Rv1 cells was linked to a 35-kb intragenic tandem duplication of AR exon 3 and flanking

274 and HPF1 We found that massive expansion of intragenic tandem repeats within the N-terminal domain o

275 In contrast, the PRC2 subunit Eed binds an intragenic Tbx3 enhancer to oppose Dpf2-dependent Tbx3 e

276 of yeast genes and revealed many examples of intragenic TL heterogeneity.

277 lloproteinase (MMP) genes MMP1 and MMP10 and intragenic to MMP2.

278 o promoters, one of which requires sequences intragenic to Rv0250c for maximum expression.

279 mplex FACT mutants, including an increase in intragenic transcription and the accumulation of free hi

280 Together, our results reveal intragenic transcription as a unique mechanism to downre

281 promotes the cellular fitness by inhibiting intragenic transcription from AT-rich target regions, pr

282 oss of both MvaT and MvaU leads to increased intragenic transcription from loci directly controlled b

283 rol alternative splicing or prevent spurious intragenic transcription in animals.

284 Widespread intragenic transcription initiation has been observed in

285 the ability of H-NS-like proteins to repress intragenic transcription is a universal function of thes

286 nstrated that the short isoforms result from intragenic transcription of ASE1, which depends on the S

287 Ethanol also caused aberrant intragenic transcription termination for mRNAs with low

288 reases intragenic H3K4me3, increases cryptic intragenic transcription, and inhibits transcriptional e

289 ith specific chromatin regulators to inhibit intragenic transcription.

290 e in transcribed regions poses a barrier for intragenic transcription.

291 ic interactions indicative of suppression of intragenic transcription.

292 a unique nucleotide frequency for initiating intragenic transcription.

293 Although intragenic transcripts are widely expressed [1], their r

294 Intragenic transcripts initiate within the coding region

295 ety of RNAs including numerous antisense and intragenic transcripts, leaderless RNAs, long untranslat

296 silencing transposable elements and aberrant intragenic transcripts.

297 Thus, the intragenic UBI4 promoter is critical to preventing ubiqu

298 ain has (i) fostered accumulation of cryptic intragenic variation and (ii) enabled unmasking of such

299 ce, the pleiotropic mechanisms by which this intragenic variation contributes to lifespan regulation

300 Intragenic variation in codon bias and elongation rate i