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On page 1 showing 1 ~ 20 papers out of 1,024 papers

Multifactorial analysis of terminator performance on heterologous gene expression in Physcomitrella.

  • Paul Alexander Niederau‎ et al.
  • Plant cell reports‎
  • 2024‎

Characterization of Physcomitrella 3'UTRs across different promoters yields endogenous single and double terminators for usage in molecular pharming. The production of recombinant proteins for health applications accounts for a large share of the biopharmaceutical market. While many drugs are produced in microbial and mammalian systems, plants gain more attention as expression hosts to produce eukaryotic proteins. In particular, the good manufacturing practice (GMP)-compliant moss Physcomitrella (Physcomitrium patens) has outstanding features, such as excellent genetic amenability, reproducible bioreactor cultivation, and humanized protein glycosylation patterns. In this study, we selected and characterized novel terminators for their effects on heterologous gene expression. The Physcomitrella genome contains 53,346 unique 3'UTRs (untranslated regions) of which 7964 transcripts contain at least one intron. Over 91% of 3'UTRs exhibit more than one polyadenylation site, indicating the prevalence of alternative polyadenylation in Physcomitrella. Out of all 3'UTRs, 14 terminator candidates were selected and characterized via transient Dual-Luciferase assays, yielding a collection of endogenous terminators performing equally high as established heterologous terminators CaMV35S, AtHSP90, and NOS. High performing candidates were selected for testing as double terminators which impact reporter levels, dependent on terminator identity and positioning. Testing of 3'UTRs among the different promoters NOS, CaMV35S, and PpActin5 showed an increase of more than 1000-fold between promoters PpActin5 and NOS, whereas terminators increased reporter levels by less than tenfold, demonstrating the stronger effect promoters play as compared to terminators. Among selected terminator attributes, the number of polyadenylation sites as well as polyadenylation signals were found to influence terminator performance the most. Our results improve the biotechnology platform Physcomitrella and further our understanding of how terminators influence gene expression in plants in general.


Design of novel peptide inhibitors against the conserved bacterial transcription terminator, Rho.

  • Gairika Ghosh‎ et al.
  • The Journal of biological chemistry‎
  • 2021‎

The transcription terminator Rho regulates many physiological processes in bacteria, such as antibiotic sensitivity, DNA repair, RNA remodeling, and so forth, and hence, is a potential antimicrobial target, which is unexplored. The bacteriophage P4 capsid protein, Psu, moonlights as a natural Rho antagonist. Here, we report the design of novel peptides based on the C-terminal region of Psu using phenotypic screening methods. The resultant 38-mer peptides, in addition to containing mutagenized Psu sequences, also contained plasmid sequences, fused to their C termini. Expression of these peptides inhibited the growth of Escherichia coli and specifically inhibited Rho-dependent termination in vivo. Peptides 16 and 33 exhibited the best Rho-inhibitory properties in vivo. Direct high-affinity binding of these two peptides to Rho also inhibited the latter's RNA-dependent ATPase and transcription termination functions in vitro. These two peptides remained functional even if eight to ten amino acids were deleted from their C termini. In silico modeling and genetic and biochemical evidence revealed that these two peptides bind to the primary RNA-binding site of the Rho hexamer near its subunit interfaces. In addition, the gene expression profiles of these peptides and Psu overlapped significantly. These peptides also inhibited the growth of Mycobacteria and inhibited the activities of Rho proteins from Mycobacterium tuberculosis, Xanthomonas, Vibrio cholerae, and Salmonella enterica. Our results showed that these novel anti-Rho peptides mimic the Rho-inhibition function of the ∼42-kDa dimeric bacteriophage P4 capsid protein, Psu. We conclude that these peptides and their C-terminal deletion derivatives could provide a basis on which to design novel antimicrobial peptides.


Composite conserved promoter-terminator motifs (PeSLs) that mediate modular shuffling in the diverse T4-like myoviruses.

  • André M Comeau‎ et al.
  • Genome biology and evolution‎
  • 2014‎

The diverse T4-like phages (Tquatrovirinae) infect a wide array of gram-negative bacterial hosts. The genome architecture of these phages is generally well conserved, most of the phylogenetically variable genes being grouped together in a series hyperplastic regions (HPRs) that are interspersed among large blocks of conserved core genes. Recent evidence from a pair of closely related T4-like phages has suggested that small, composite terminator/promoter sequences (promoterearly stem loop [PeSLs]) were implicated in mediating the high levels of genetic plasticity by indels occurring within the HPRs. Here, we present the genome sequence analysis of two T4-like phages, PST (168 kb, 272 open reading frames [ORFs]) and nt-1 (248 kb, 405 ORFs). These two phages were chosen for comparative sequence analysis because, although they are closely related to phages that have been previously sequenced (T4 and KVP40, respectively), they have different host ranges. In each case, one member of the pair infects a bacterial strain that is a human pathogen, whereas the other phage's host is a nonpathogen. Despite belonging to phylogenetically distant branches of the T4-likes, these pairs of phage have diverged from each other in part by a mechanism apparently involving PeSL-mediated recombination. This analysis confirms a role of PeSL sequences in the generation of genomic diversity by serving as a point of genetic exchange between otherwise unrelated sequences within the HPRs. Finally, the palette of divergent genes swapped by PeSL-mediated homologous recombination is discussed in the context of the PeSLs' potentially important role in facilitating phage adaption to new hosts and environments.


Genetic Diversity and Demographic History of Ganoderma boninense in Oil Palm Plantations of Sarawak, Malaysia Inferred from ITS Regions.

  • Frazer Midot‎ et al.
  • Microorganisms‎
  • 2019‎

Ganoderma boninense causes basal stem rot (BSR) and is responsible for substantial economic losses to Southeast Asia's palm oil industry. Sarawak, a major producer in Malaysia, is also affected by this disease. Emergence of BSR in oil palm planted on peat throughout Sarawak is alarming as the soil type was previously regarded as non-conducive. Phylogenetic analysis indicated a single species, G. boninense as the cause of BSR in Sarawak. Information on evolutionary and demographic history for G. boninense in Sarawak inferred through informative genes is lacking. Hence, a haplotype study on single nucleotide polymorphisms in internal transcribed spacers (SNPs-ITS) of G. boninense was carried out. Sequence variations were analysed for population structure, phylogenetic and phylogeographic relationships. The internal transcribed spacers (ITS) region of 117 isolates from four populations in eight locations across Sarawak coastal areas revealed seven haplotypes. A major haplotype, designated GbHap1 (81.2%), was found throughout all sampling locations. Single nucleotide polymorphisms were observed mainly in the ITS1 region. The genetic structure was not detected, and genetic distance did not correlate with geographical distance. Haplotype network analysis suggested evidence of recent demographic expansion. Low genetic differences among populations also suggested that these isolates belong to a single G. boninense founder population adapting to oil palm as the host.


Development of a yeast heterologous expression cassette based on the promoter and terminator elements of the Eremothecium cymbalariae translational elongation factor 1α (EcTEF1) gene.

  • Tomas Linder‎
  • 3 Biotech‎
  • 2018‎

A new expression cassette (EC0) consisting of the fused 5' and 3' intergenic regions (IGRs) of the Eremothecium cymbalariae translational elongation factor 1α (EcTEF1) gene was evaluated through expression of the bacterial hygromycin B phosphotransferase (hph) resistance gene in the common baker's yeast Saccharomyces cerevisiae. Progressively shorter versions of the hph-containing EC cassette (hphEC1 though hphEC6) with trimmed 5' and 3' EcTEF1 IGRs were tested for their ability to confer resistance to hygromycin B in S. cerevisiae. Hygromycin B resistance was retained in all six generated hphEC variants up to a concentration of 400 mg/L. The hphEC6 cassette was the shortest cassette to be assayed in this study with 366 and 155 bp of the EcTEF1 5' and 3' IGRs, respectively. When tested for deletion of the S. cerevisiae proline oxidase gene PUT1, the hphEC6 cassette was shown to successfully act as a selection marker on hygromycin B-containing medium. The hphEC6 cassette could be placed immediately adjacent to a kanMX4 G418 disulfate resistance marker without any discernable effect on the ability of the yeast to grow in the presence of both hygromycin B and G418 disulfate. Co-cultivation experiments under non-selective conditions demonstrated that a PUT1 deletion strain carrying the hphEC6 cassette displayed equivalent fitness to an otherwise isogenic PUT1 deletion strain carrying the kanMX4 cassette.


Investigation of natural infection of Phlebotomine (Diptera: Psychodidae) by Leishmania in Tunisian endemic regions.

  • Melek Chaouch‎ et al.
  • Parasite epidemiology and control‎
  • 2021‎

Leishmaniases are caused by protozoan parasites of the genus Leishmania transmitted by females blood-feeding phlebotomine insects (Diptera: Psychodidae). In Tunisia, cutaneous and visceral leishmaniases are of public health concern. In Tunisia, 17 species of phlebotomine sand flies are described. Here we investigate natural infection in Tunisian mixed foci regions of leishmaniases. We trap female sandflies during the Leishmania transmission season in the country's central-eastern and northern parts. We investigate Leishmania infection using PCR-RFLP targeting the ITS1 ribosomal DNA, followed by enzymatic digestion with HaeIII; then, we identify sand flies using molecular methodologies. We confirm the presence of Phlebotomus papatasi and Phlebotomus perniciosus infected by L. major and L. infantum parasites in Tunisia.


5' and 3' Untranslated Regions Strongly Enhance Performance of Geminiviral Replicons in Nicotiana benthamiana Leaves.

  • Andrew G Diamos‎ et al.
  • Frontiers in plant science‎
  • 2016‎

We previously reported a recombinant protein production system based on a geminivirus replicon that yields high levels of vaccine antigens and monoclonal antibodies in plants. The bean yellow dwarf virus (BeYDV) replicon generates massive amounts of DNA copies, which engage the plant transcription machinery. However, we noticed a disparity between transcript level and protein production, suggesting that mRNAs could be more efficiently utilized. In this study, we systematically evaluated genetic elements from human, viral, and plant sources for their potential to improve the BeYDV system. The tobacco extensin terminator enhanced transcript accumulation and protein production compared to other commonly used terminators, indicating that efficient transcript processing plays an important role in recombinant protein production. Evaluation of human-derived 5' untranslated regions (UTRs) indicated that many provided high levels of protein production, supporting their cross-kingdom function. Among the viral 5' UTRs tested, we found the greatest enhancement with the tobacco mosaic virus omega leader. An analysis of the 5' UTRs from the Arabidopsis thaliana and Nicotinana benthamiana photosystem I K genes found that they were highly active when truncated to include only the near upstream region, providing a dramatic enhancement of transgene production that exceeded that of the tobacco mosaic virus omega leader. The tobacco Rb7 matrix attachment region inserted downstream from the gene of interest provided significant enhancement, which was correlated with a reduction in plant cell death. Evaluation of Agrobacterium strains found that EHA105 enhanced protein production and reduced cell death compared to LBA4301 and GV3101. We used these improvements to produce Norwalk virus capsid protein at >20% total soluble protein, corresponding to 1.8 mg/g leaf fresh weight, more than twice the highest level ever reported in a plant system. We also produced the monoclonal antibody rituximab at 1 mg/g leaf fresh weight.


Role of deleterious single nucleotide variants in the coding regions of TNFAIP3 for Japanese autoimmune hepatitis with cirrhosis.

  • Takashi Higuchi‎ et al.
  • Scientific reports‎
  • 2019‎

Autoimmune hepatitis (AIH) is an autoimmune liver disease and cirrhosis is sometimes complicated with AIH at diagnosis, influencing its prognosis. TNFAIP3 gene encodes A20, an inhibitor of nuclear factor-κB pathway, and is a susceptibility gene for autoimmune diseases. We investigated deleterious variants in the coding regions of TNFAIP3 gene of Japanese AIH patients or those with cirrhosis. The deleterious variants in the coding regions of TNFAIP3 gene were analyzed by the cycle sequencing method and the frequencies of deleterious TNFAIP3 alleles of AIH or AIH with cirrhosis were compared with those of Japanese controls. The deleterious alleles in TNFAIP3 were not associated with AIH. A significant association was shown for the deleterious alleles in TNFAIP3 (P = 0.0180, odds ratio (OR) 4.28, 95% confidence interval (CI) 1.53-11.95) with AIH with cirrhosis at presentation. The serum IgM levels in AIH patients with deleterious alleles in TNFAIP3 were tended to be lower than those without (P = 0.0152, Q = 0.1216). The frequency of deleterious alleles in TNFAIP3 was higher in the AIH subset without the DRB1 risk alleles than that with (P = 0.0052, OR 5.10, 95%CI 1.55-16.74). The deleterious alleles in TNFAIP3were associated with AIH with cirrhosis.


Assessing the links among environmental contaminants, endocrinology, and parasites to understand amphibian declines in montane regions of Costa Rica.

  • Christopher J Leary‎ et al.
  • PloS one‎
  • 2018‎

Amphibians inhabiting montane riparian zones in the Neotropics are particularly vulnerable to decline, but the reasons are poorly understood. Because environmental contaminants, endocrine disruption, and pathogens often figure prominently in amphibian declines it is imperative that we understand how these factors are potentially interrelated to affect montane populations. One possibility is that increased precipitation associated with global warming promotes the deposition of contaminants in montane regions. Increased exposure to contaminants, in turn, potentially elicits chronic elevations in circulating stress hormones that could contribute to montane population declines by compromising resistance to pathogens and/or production of sex steroids regulating reproduction. Here, we test this hypothesis by examining contaminant levels, stress and sex steroid levels, and nematode abundances in male drab treefrogs, Smilisca sordida, from lowland and montane populations in Costa Rica. We found no evidence that montane populations were more likely to possess contaminants (i.e., organochlorine, organophosphate and carbamate pesticides or benzidine and chlorophenoxy herbicides) than lowland populations. We also found no evidence of elevational differences in circulating levels of the stress hormone corticosterone, estradiol or progesterone. However, montane populations possessed lower androgen levels, hosted more nematode species, and had higher nematode abundances than lowland populations. Although these results suggested that nematodes contributed to lower androgens in montane populations, we were unable to detect a significant inverse relationship between nematode abundance and androgen level. Our results suggest that montane populations of this species are not at greater risk of exposure to contaminants or chronic stress, but implicate nematodes and compromised sex steroid levels as potential threats to montane populations.


Genetic Heterogeneity in Algerian Human Populations.

  • Asmahan Bekada‎ et al.
  • PloS one‎
  • 2015‎

The demographic history of human populations in North Africa has been characterized by complex processes of admixture and isolation that have modeled its current gene pool. Diverse genetic ancestral components with different origins (autochthonous, European, Middle Eastern, and sub-Saharan) and genetic heterogeneity in the region have been described. In this complex genetic landscape, Algeria, the largest country in Africa, has been poorly covered, with most of the studies using a single Algerian sample. In order to evaluate the genetic heterogeneity of Algeria, Y-chromosome, mtDNA and autosomal genome-wide makers have been analyzed in several Berber- and Arab-speaking groups. Our results show that the genetic heterogeneity found in Algeria is not correlated with geography or linguistics, challenging the idea of Berber groups being genetically isolated and Arab groups open to gene flow. In addition, we have found that external sources of gene flow into North Africa have been carried more often by females than males, while the North African autochthonous component is more frequent in paternally transmitted genome regions. Our results highlight the different demographic history revealed by different markers and urge to be cautious when deriving general conclusions from partial genomic information or from single samples as representatives of the total population of a region.


Genetic Screening of the Usher Syndrome in Cuba.

  • Elayne E Santana‎ et al.
  • Frontiers in genetics‎
  • 2019‎

Usher syndrome (USH) is a recessive inherited disease characterized by sensorineural hearing loss, retinitis pigmentosa, and sometimes, vestibular dysfunction. Although the molecular epidemiology of Usher syndrome has been well studied in Europe and United States, there is a lack of studies in other regions like Africa or Central and South America.


Updating the Genetic Landscape of Inherited Retinal Dystrophies.

  • Belén García Bohórquez‎ et al.
  • Frontiers in cell and developmental biology‎
  • 2021‎

Inherited retinal dystrophies (IRD) are a group of diseases characterized by the loss or dysfunction of photoreceptors and a high genetic and clinical heterogeneity. Currently, over 270 genes have been associated with IRD which makes genetic diagnosis very difficult. The recent advent of next generation sequencing has greatly facilitated the diagnostic process, enabling to provide the patients with accurate genetic counseling in some cases. We studied 92 patients who were clinically diagnosed with IRD with two different custom panels. In total, we resolved 53 patients (57.6%); in 12 patients (13%), we found only one mutation in a gene with a known autosomal recessive pattern of inheritance; and 27 patients (29.3%) remained unsolved. We identified 120 pathogenic or likely pathogenic variants; 30 of them were novel. Among the cone-rod dystrophy patients, ABCA4 was the most common mutated gene, meanwhile, USH2A was the most prevalent among the retinitis pigmentosa patients. Interestingly, 10 families carried pathogenic variants in more than one IRD gene, and we identified two deep-intronic variants previously described as pathogenic in ABCA4 and CEP290. In conclusion, the IRD study through custom panel sequencing demonstrates its efficacy for genetic diagnosis, as well as the importance of including deep-intronic regions in their design. This genetic diagnosis will allow patients to make accurate reproductive decisions, enroll in gene-based clinical trials, and benefit from future gene-based treatments.


Genetic isolation in an endemic African habitat specialist.

  • Natalie Dos Remedios‎ et al.
  • The Ibis‎
  • 2017‎

The Chestnut-banded Plover Charadrius pallidus is a Near-Threatened shorebird species endemic to mainland Africa. We examined levels of genetic differentiation between its two morphologically and geographically distinct subspecies, C. p. pallidus in southern Africa (population size 11 000-16 000) and C. p. venustus in eastern Africa (population size 6500). In contrast to other plover species that maintain genetic connectivity over thousands of kilometres across continental Africa, we found profound genetic differences between remote sampling sites. Phylogenetic network analysis based on four nuclear and two mitochondrial gene regions, and population genetic structure analyses based on 11 microsatellite loci, indicated strong genetic divergence, with 2.36% mitochondrial sequence divergence between individuals sampled in Namibia (southern Africa) and those of Kenya and Tanzania (eastern Africa). This distinction between southern and eastern African populations was also supported by highly distinct genetic clusters based on microsatellite markers (global FST  = 0.309, GST' = 0.510, D = 0.182). Behavioural factors that may promote genetic differentiation in this species include habitat specialization, monogamous mating behaviour and sedentariness. Reliance on an extremely small number of saline lakes for breeding and limited dispersal between populations are likely to promote reproductive and genetic isolation between eastern and southern Africa. We suggest that the two Chestnut-banded Plover subspecies may warrant elevation to full species status. To assess this distinction fully, additional sample collection will be needed, with analysis of genetic and phenotypic traits from across the species' entire breeding range.


Identification of plastid genomic regions inferring species identity from de novo plastid genome assembly of 14 Korean-native Iris species (Iridaceae).

  • Yang Jae Kang‎ et al.
  • PloS one‎
  • 2020‎

Iris is one of the largest genera in the family Iridaceae, comprising hundreds of species, including numerous economically important horticultural plants used in landscape gardening and herbal medicine. Improved taxonomic classification of Iris species, particularly the endangered Korean-native Iris, is needed for correct species delineation. To this end, identification of diverse genetic markers from Iris genomes would facilitate molecular identification and resolve ambiguous classifications from molecular analyses; however, only two Iris plastid genomes, from Iris gatesii and Iris sanguinea, have been sequenced. Here, we used high-throughput next-generation sequencing, combined with Sanger sequencing, to construct the plastid genomes of 14 Korean-native Iris species with one outgroup and predict their gene content. Using these data, combined with previously published plastid genomes from Iris and one outgroup (Sisyrinchium angustifolium), we constructed a Bayesian phylogenetic tree showing clear speciation among the samples. We further identified sub-genomic regions that have undergone neutral evolution and accurately recapitulate Bayesian-inferred speciation. These contain key markers that could be used to identify and classify Iris samples into taxonomic clades. Our results confirm previously reported speciation patterns and resolve questionable relationships within the Iris genus. These data also provide a valuable resource for studying genetic diversity and refining phylogenetic relationships between Iris species.


Genetic overlap between apparently sporadic motor neuron diseases.

  • Marka van Blitterswijk‎ et al.
  • PloS one‎
  • 2012‎

Progressive muscular atrophy (PMA) and amyotrophic lateral sclerosis (ALS) are devastating motor neuron diseases (MNDs), which result in muscle weakness and/or spasticity. We compared mutation frequencies in genes known to be associated with MNDs between patients with apparently sporadic PMA and ALS. A total of 261 patients with adult-onset sporadic PMA, patients with sporadic ALS, and control subjects of Dutch descent were obtained at national referral centers for neuromuscular diseases in The Netherlands. Sanger sequencing was used to screen these subjects for mutations in the coding regions of superoxide dismutase-1 (SOD1), angiogenin (ANG), fused in sarcoma/translated in liposarcoma (FUS/TLS), TAR DNA-binding protein 43 (TARDBP), and multivesicular body protein 2B (CHMP2B). In our cohort of PMA patients we identified two SOD1 mutations (p.D90A, p.I113T), one ANG mutation (p.K17I), one FUS/TLS mutation (p.R521H), one TARDBP mutation (p.N352S), and one novel CHMP2B mutation (p.R69Q). The mutation frequency of these genes was similar in sporadic PMA (2.7%) and ALS (2.0%) patients, and therefore, our findings demonstrate a genetic overlap between apparently sporadic PMA and ALS.


Spatial biology of Ising-like synthetic genetic networks.

  • Kevin Simpson‎ et al.
  • BMC biology‎
  • 2023‎

Understanding how spatial patterns of gene expression emerge from the interaction of individual gene networks is a fundamental challenge in biology. Developing a synthetic experimental system with a common theoretical framework that captures the emergence of short- and long-range spatial correlations (and anti-correlations) from interacting gene networks could serve to uncover generic scaling properties of these ubiquitous phenomena.


Cerebral Microbleed Burdens in Specific Brain Regions Are Associated With Disease Severity of Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy.

  • Chih-Ping Chung‎ et al.
  • Journal of the American Heart Association‎
  • 2020‎

Background Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, caused by NOTCH3 mutations, is characterized by recurrent ischemic strokes and progressive cognitive decline. It remains unclear whether cerebral microbleeds (CMBs) can serve as a surrogate marker for disease progression in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. We aimed to investigate the CMB burdens in NOTCH3 mutation carriers at different disease stages and test their associations with cognitive performance. Methods and Results Forty-nine individuals carrying NOTCH3 cysteine-altering mutations received brain magnetic resonance imaging with T1-weighted and susceptibility-weighted images. Whole brain images were segmented into 14 regions using Statistical Parametric Mapping and FreeSurfer software, and semiautomatic methods were used to locate and quantify the number and volume of CMBs. In our study participants, the median of CMB counts was 13, with a wide individual variation (range, 0-286). CMBs were most frequently present in thalamus, followed by temporal lobe. In the whole brain, the CMB counts and CMB volume ratios (ie, CMB volume divided by the volume of corresponding brain region) gradually increased as the disease advanced. CMB counts in the thalamus and temporal and frontal lobes increased more rapidly than other brain regions as disease progressed. There were significant associations between Mini-Mental State Examination scores and CMB counts in the frontal lobe, temporal lobe, and pons. Conclusions CMBs may have an influential role in the clinical manifestations of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy. CMB burdens and their distribution in different brain regions may be capable to serve as a disease marker for monitoring the disease severity of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.


Autosomal recessive retinitis pigmentosa with homozygous rhodopsin mutation E150K and non-coding cis-regulatory variants in CRX-binding regions of SAMD7.

  • Kristof Van Schil‎ et al.
  • Scientific reports‎
  • 2016‎

The aim of this study was to unravel the molecular pathogenesis of an unusual retinitis pigmentosa (RP) phenotype observed in a Turkish consanguineous family. Homozygosity mapping revealed two candidate genes, SAMD7 and RHO. A homozygous RHO mutation c.448G > A, p.E150K was found in two affected siblings, while no coding SAMD7 mutations were identified. Interestingly, four non-coding homozygous variants were found in two SAMD7 genomic regions relevant for binding of the retinal transcription factor CRX (CRX-bound regions, CBRs) in these affected siblings. Three variants are located in a promoter CBR termed CBR1, while the fourth is located more downstream in CBR2. Transcriptional activity of these variants was assessed by luciferase assays and electroporation of mouse retinal explants with reporter constructs of wild-type and variant SAMD7 CBRs. The combined CBR2/CBR1 variant construct showed significantly decreased SAMD7 reporter activity compared to the wild-type sequence, suggesting a cis-regulatory effect on SAMD7 expression. As Samd7 is a recently identified Crx-regulated transcriptional repressor in retina, we hypothesize that these SAMD7 variants might contribute to the retinal phenotype observed here, characterized by unusual, recognizable pigment deposits, differing from the classic spicular intraretinal pigmentation observed in other individuals homozygous for p.E150K, and typically associated with RP in general.


Patterns of nucleotide diversity at the regions encompassing the Drosophila insulin-like peptide (dilp) genes: demography vs. positive selection in Drosophila melanogaster.

  • Sara Guirao-Rico‎ et al.
  • PloS one‎
  • 2013‎

In Drosophila, the insulin-signaling pathway controls some life history traits, such as fertility and lifespan, and it is considered to be the main metabolic pathway involved in establishing adult body size. Several observations concerning variation in body size in the Drosophila genus are suggestive of its adaptive character. Genes encoding proteins in this pathway are, therefore, good candidates to have experienced adaptive changes and to reveal the footprint of positive selection. The Drosophila insulin-like peptides (DILPs) are the ligands that trigger the insulin-signaling cascade. In Drosophila melanogaster, there are several peptides that are structurally similar to the single mammalian insulin peptide. The footprint of recent adaptive changes on nucleotide variation can be unveiled through the analysis of polymorphism and divergence. With this aim, we have surveyed nucleotide sequence variation at the dilp1-7 genes in a natural population of D. melanogaster. The comparison of polymorphism in D. melanogaster and divergence from D. simulans at different functional classes of the dilp genes provided no evidence of adaptive protein evolution after the split of the D. melanogaster and D. simulans lineages. However, our survey of polymorphism at the dilp gene regions of D. melanogaster has provided some evidence for the action of positive selection at or near these genes. The regions encompassing the dilp1-4 genes and the dilp6 gene stand out as likely affected by recent adaptive events.


Hypoinsulinaemic, hypoketotic hypoglycaemia due to mosaic genetic activation of PI3-kinase.

  • Sarah M Leiter‎ et al.
  • European journal of endocrinology‎
  • 2017‎

Genetic activation of the insulin signal-transducing kinase AKT2 causes syndromic hypoketotic hypoglycaemia without elevated insulin. Mosaic activating mutations in class 1A phospatidylinositol-3-kinase (PI3K), upstream from AKT2 in insulin signalling, are known to cause segmental overgrowth, but the metabolic consequences have not been systematically reported. We assess the metabolic phenotype of 22 patients with mosaic activating mutations affecting PI3K, thereby providing new insight into the metabolic function of this complex node in insulin signal transduction.


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