Die Reproduktion von Macaranga (Euphorbiaceae) in Südostasien : Bestäubung durch Thripse und Kastration durch Pflanzenameisen

Obligate Mutualismen gehören zu den bevorzugten Studienobjekten zur Erforschung der Mechanismen und Faktoren, welche Artenvielfalt hervorbringen und erhalten. Die Bestäubung der diözischen Pionierbaumgattung Macaranga (Euphorbiaceae) war bislang unbekannt, und Untersuchungen zur Myrmekophytie in Macaranga beschränkten sich in der Vergangenheit auf die Jugendphase der Assoziation mit Ameisen. Während als gesichert galt, dass die Partnerorganismen in Myrmekophytie- und Bestäubungssystemen voneinander profitieren, blieben Konflikte bzw. Konfliktlösungen in diesen Mutualismen weitgehend unerforscht. Ziel der vorliegenden Untersuchung war es, die Bestäubung der Ameisenpflanzengattung Macaranga aufzuklären und potentielle Konflikte der Fortpflanzung von Macaranga mit dem Myrmekophytiesystem zu analysieren. Die insgesamt 16-monatigen Freilanduntersuchungen in Malaysia und Indonesien wurden in 6 Aufenthalten (1998-2001) durchgeführt. Von 27 Macaranga-Arten wurden Daten zur Blütenbiologie erhoben. Die Hauptuntersuchungsart war M. hullettii. Zusätzlich fanden Untersuchungen der Infloreszenzmorphologie aller westmalesischen Macaranga-Arten in den Herbarien des Forest Research Institute Malaysia (FRIM) und des Nationaal Herbarium Nederland in Leiden statt. 1) Die Bestäubung von Macaranga Von 27 der 61 Macaranga-Arten, welche auf der Halbinsel Malaysia und den großen Sundainseln Borneo und Sumatra vorkommen, wurden insgesamt 28544 Blütenbesucher gesammelt und das Verhalten der dominierenden Blütenbesucher beobachtet. Bei 52% der Arten dominierte eine Thripsart der Gattung Neoheegeria (Phlaeothripinae; Thysanoptera), bei 15% Thripse der Gattung Mesothrips (Phlaeothripinae, Thysanoptera), bei 11% Wanzen (Miridae und Anthocoridae; Heteroptera), bei 4% Thripse der Tribus Terebrantia, bei 4% Rüsselkäfer, und bei 15% diverse andere Insekten der Ordnungen Coleoptera, Hymenoptera und Diptera. Für den dominierenden Blütenbesucher Neoheegeria spec. wird gezeigt, dass er als effektiver Bestäuber von M. hullettii fungiert. Der Pollentransfer von männlichen zu weiblichen Bäumen und der Samenansatz nach ausschließlichem Zugang von Thripsen zu den Blüten konnte nachgewiesen werden. Die Thripse durchlaufen ihre Larvalentwicklung in weiblichen und männlichen Blütenständen. Der Vergleich der Blühzeiten von M. hullettii und der Entwicklungsdauer von Neoheegeria spec. erbrachte, dass die Dauer der Anthese des Wirtes und die der Entwicklung der Thripse aufeinander abgestimmt ist. Männliche Blütenstände öffnen ihre Knospen zeitlich vor den weiblichen Blütenständen, sodass eine Vermehrung der Thrips-Bestäuber-Population in männlichen Bäumen vor dem Beginn der Blühzeiten beider Geschlechter stattfinden kann. Die Analyse der Bestäubungstypen zeigte, dass blütenbedeckende Hüllblättchen mit Trichomnektarien als Belohnung für bestäubende Thripse und Wanzen dienen. Dieses Merkmal wird für thrips- und wanzenbestäubte Macaranga-Arten als homolog angesehen. Die Blütendeckblättchen umschließen die Blüten so eng, dass nur kleinsten Insekten der Zugang zu den Blüten gewährt wird. Neoheegeria-bestäubte Macaranga-Arten zeichnen sich durch ein reduziertes Androeceum und ein wenig strukturiertes Tectum der Pollenkörner aus. Die Bestimmung der Blühzeiten von 7 sympatrischen Macaranga-Arten erbrachte, dass Arten mit den gleichen Bestäubern zeitlich isoliert sind. Dagegen weisen Arten, deren Blühzeiten sich überschneiden, verschiedene Bestäuber auf. 2) Interaktionen der Reproduktion von Macaranga mit der Myrmekophytie Konflikte zwischen den Bestäubern und den Partnerameisen von Macaranga konnten nicht beobachtet werden. Dafür trat ein anderer, schwerwiegender Konflikt in Erscheinung, der drastische, negative Auswirkungen auf die Fortpflanzung von Macaranga hatte. Die Partnerameisen zerstörten zeitweise die Blüten ihrer Wirte. Dieses Kastrations-Verhalten zeigte sich bei mehreren Crematogaster-Arten, die verschiedene Macaranga-Arten besiedeln. Im Gombaktal, ein Hauptuntersuchungsgebiet im Tieflandregenwald Westmalaysias, trat das Kastrationsphänomen am häufigsten bei M. hullettii auf. 56% der Population wurde von ihren Ameisenbesiedlern (hauptsächlich C. msp. 4) kastriert. Das Phänomen wies eine ungleichmäßige Verteilung auf: Blütenzerstörung korrelierte signifikant negativ mit der Baumgröße. Die Analyse verschiedener Kolonie- und WirtspflanzenParameter ergab Hinweise, dass nicht Nahrungs- bzw. Nistraumlimitierung sondern die Koloniegröße ein entscheidender Faktor für dieses Verhalten war. Ab einer bestimmten Koloniegröße setzte nicht nur das Kastrationsverhalten aus, sondern auch die Außenaktivität der Ameisen nahm stark ab. Gleichzeitig stieg die Brutzunahme deutlich an, und die regelmäßige Geschlechtstierproduktion setzte ein. Die Ergebnisse deuten darauf hin, dass Crematogaster (Decacrema), welche noch nicht ihre reife Koloniegröße erreicht haben, die Blüten ihres Wirtsbaumes zerstören, wenn dieser vor den Ameisen mit der reproduktiven Phase einsetzt. Aufgrund der daraus resultierenden Kosten für die Wirtspflanze könnte die Crematogaster-Art (msp. 4) als "unpassender" Partner von M. hullettii angesehen werden. Während die Schutzwirkung gegen Herbivorie an jungen Blättern durch C. msp. 4 aus früheren Untersuchungen gut belegt ist, fungiert diese Ameisenart durch ihr Kastrationsverhalten teilweise als Parasit in der Assoziation mit M. hullettii. Es wird ein Modell vorgeschlagen, in dem die Kastration als ein Konflikt zwischen den Partnern über das Einsetzen der Reproduktionsphase angesehen wird. "Passende" Partner sind folglich daran erkennbar, dass sich das Einsetzen ihrer Reproduktionsphasen weitgehend synchronisiert hat. Aus dieser Hypothese ergibt sich, dass der dominierende Ameisenbesiedler C. msp. 4 von M. hullettii im Tiefland des Untersuchungsgebietes nicht als "echter" Mutualist anzusehen ist. In den submontanen Regionen ist M. hullettii ausschließlich mit C. msp. 3 assoziiert. Letztere Crematogaster-Art wird als der eigentliche "passende" Partner vorgeschlagen, während C. msp. 4 als "echter" Mutualist einer zweiten Macaranga-Art, M. bancana, diskutiert wird. Auf der Basis der gewonnenen Ergebnisse und der Grundlage von jüngsten phylogenetischen Analysen von Macaranga werden Überlegungen zur Evolution der Bestäubungs- und Myrmekophytiesysteme vorgestellt

Behavioral phenotype in five individuals with de novo mutations within the GRIN2B gene

Background: Intellectual disability (ID) is often associated with behavioral problems or disorders. Mutations in the GRIN2B gene (MRD6, MIM613970) have been identified as a common cause of ID (prevalence of 0.5 – 1% in individuals with ID) associated with EEG and behavioral problems. Methods: We assessed five GRIN2B mutation carriers aged between 3 and 14 years clinically and via standardized questionnaires to delineate a detailed behavioral phenotype. Parents and teachers rated problem behavior of their affected children by completing the Developmental Behavior Checklist (DBC) and the Conners’ Rating Scales Revised (CRS-R:L). Results: All individuals had mild to severe ID and needed guidance in daily routine. They showed characteristic behavior problems with prominent hyperactivity, impulsivity, distractibility and a short attention span. Stereotypies, sleeping problems and a friendly but boundless social behavior were commonly reported. Conclusion: Our observations provide an initial delineation of the behavioral phenotype of GRIN2B mutation carriers

Clinical spectrum of females with HCCS mutation: from no clinical signs to a neonatal lethal form of the microphthalmia with linear skin defects (MLS) syndrome

Background: Segmental Xp22.2 monosomy or a heterozygous HCCS mutation is associated with the microphthalmia with linear skin defects (MLS) or MIDAS (microphthalmia, dermal aplasia, and sclerocornea) syndrome, an X-linked disorder with male lethality. HCCS encodes the holocytochrome c-type synthase involved in mitochondrial oxidative phosphorylation (OXPHOS) and programmed cell death. Methods: We characterized the X-chromosomal abnormality encompassing HCCS or an intragenic mutation in this gene in six new female patients with an MLS phenotype by cytogenetic analysis, fluorescence in situ hybridization, sequencing, and quantitative real-time PCR. The X chromosome inactivation (XCI) pattern was determined and clinical data of the patients were reviewed. Results: Two terminal Xp deletions of ≥11.2 Mb, two submicroscopic copy number losses, one of ~850 kb and one of ≥3 Mb, all covering HCCS, 1 nonsense, and one mosaic 2-bp deletion in HCCS are reported. All females had a completely (>98:2) or slightly skewed (82:18) XCI pattern. The most consistent clinical features were microphthalmia/anophthalmia and sclerocornea/corneal opacity in all patients and congenital linear skin defects in 4/6. Additional manifestations included various ocular anomalies, cardiac defects, brain imaging abnormalities, microcephaly, postnatal growth retardation, and facial dysmorphism. However, no obvious clinical sign was observed in three female carriers who were relatives of one patient. Conclusion: Our findings showed a wide phenotypic spectrum ranging from asymptomatic females with an HCCS mutation to patients with a neonatal lethal MLS form. Somatic mosaicism and the different ability of embryonic cells to cope with an OXPHOS defect and/or enhanced cell death upon HCCS deficiency likely underlie the great variability in phenotypes

Phenotypic and molecular insights into CASK-related disorders in males

Background: Heterozygous loss-of-function mutations in the X-linked CASK gene cause progressive microcephaly with pontine and cerebellar hypoplasia (MICPCH) and severe intellectual disability (ID) in females. Different CASK mutations have also been reported in males. The associated phenotypes range from nonsyndromic ID to Ohtahara syndrome with cerebellar hypoplasia. However, the phenotypic spectrum in males has not been systematically evaluated to date. Methods: We identified a CASK alteration in 8 novel unrelated male patients by targeted Sanger sequencing, copy number analysis (MLPA and/or FISH) and array CGH. CASK transcripts were investigated by RT-PCR followed by sequencing. Immunoblotting was used to detect CASK protein in patient-derived cells. The clinical phenotype and natural history of the 8 patients and 28 CASK-mutation positive males reported previously were reviewed and correlated with available molecular data. Results: CASK alterations include one nonsense mutation, one 5-bp deletion, one mutation of the start codon, and five partial gene deletions and duplications; seven were de novo, including three somatic mosaicisms, and one was familial. In three subjects, specific mRNA junction fragments indicated in tandem duplication of CASK exons disrupting the integrity of the gene. The 5-bp deletion resulted in multiple aberrant CASK mRNAs. In fibroblasts from patients with a CASK loss-of-function mutation, no CASK protein could be detected. Individuals who are mosaic for a severe CASK mutation or carry a hypomorphic mutation still showed detectable amount of protein. Conclusions: Based on eight novel patients and all CASK-mutation positive males reported previously three phenotypic groups can be distinguished that represent a clinical continuum: (i) MICPCH with severe epileptic encephalopathy caused by hemizygous loss-of-function mutations, (ii) MICPCH associated with inactivating alterations in the mosaic state or a partly penetrant mutation, and (iii) syndromic/nonsyndromic mild to severe ID with or without nystagmus caused by CASK missense and splice mutations that leave the CASK protein intact but likely alter its function or reduce the amount of normal protein. Our findings facilitate focused testing of the CASK gene and interpreting sequence variants identified by next-generation sequencing in cases with a phenotype resembling either of the three groups

POLR3A variants with striatal involvement and extrapyramidal movement disorder

Biallelic variants in POLR3A cause 4H leukodystrophy, characterized by hypomyelination in combination with cerebellar and pyramidal signs and variable non-neurological manifestations. Basal ganglia are spared in 4H leukodystrophy, and dystonia is not prominent. Three patients with variants in POLR3A, an atypical presentation with dystonia, and MR involvement of putamen and caudate nucleus (striatum) and red nucleus have previously been reported. Genetic, clinical findings and 18 MRI scans from nine patients with homozygous or compound heterozygous POLR3A variants and predominant striatal changes were retrospectively reviewed in order to characterize the striatal variant of POLR3A-associated disease. Prominent extrapyramidal involvement was the predominant clinical sign in all patients. The three youngest children were severely affected with muscle hypotonia, impaired head control, and choreic movements. Presentation of the six older patients was milder. Two brothers diagnosed with juvenile parkinsonism were homozygous for the c.1771-6C > G variant in POLR3A; the other seven either carried c.1771-6C > G (n = 1) or c.1771-7C > G (n = 7) together with another variant (missense, synonymous, or intronic). Striatal T2-hyperintensity and atrophy together with involvement of the superior cerebellar peduncles were characteristic. Additional MRI findings were involvement of dentate nuclei, hila, or peridentate white matter (3, 6, and 4/9), inferior cerebellar peduncles (6/9), red nuclei (2/9), and abnormal myelination of pyramidal and visual tracts (6/9) but no frank hypomyelination. Clinical and MRI findings in patients with a striatal variant of POLR3A-related disease are distinct from 4H leukodystrophy and associated with one of two intronic variants, c.1771-6C > G or c.1771-7C > G, in combination with another POLR3A variant

Somatic insulin signaling regulates a germline starvation response in Drosophila egg chambers

AbstractEgg chambers from starved Drosophila females contain large aggregates of processing (P) bodies and cortically enriched microtubules. As this response to starvation is rapidly reversed upon re-feeding females or culturing egg chambers with exogenous bovine insulin, we examined the role of endogenous insulin signaling in mediating the starvation response. We found that systemic Drosophila insulin-like peptides (dILPs) activate the insulin pathway in follicle cells, which then regulate both microtubule and P body organization in the underlying germline cells. This organization is modulated by the motor proteins Dynein and Kinesin. Dynein activity is required for microtubule and P body organization during starvation, while Kinesin activity is required during nutrient-rich conditions. Blocking the ability of egg chambers to form P body aggregates in response to starvation correlated with reduced progeny survival. These data suggest a potential mechanism to maximize fecundity even during periods of poor nutrient availability, by mounting a protective response in immature egg chambers

Identification of FOXP1 Deletions in Three Unrelated Patients with Mental Retardation and Significant Speech and Language Deficits

Mental retardation affects 2-3% of the population and shows a high heritability. Neurodevelopmental disorders that include pronounced impairment in language and speech skills occur less frequently. For most cases, the molecular basis of mental retardation with or without speech and language disorder is unknown due to the heterogeneity of underlying genetic factors. We have used molecular karyotyping on 1523 patients with mental retardation to detect copy number variations (CNVs) including deletions or duplications. These studies revealed three heterozygous overlapping deletions solely affecting the forkhead box P1 (FOXP1) gene. All three patients had moderate mental retardation and significant language and speech deficits. Since our results are consistent with a de novo occurrence of these deletions, we considered them as causal although we detected a single large deletion including FOXP1 and additional genes in 4104 ancestrally matched controls. These findings are of interest with regard to the structural and functional relationship between FOXP1 and FOXP2. Mutations in FOXP2 have been previously related to monogenic cases of developmental verbal dyspraxia. Both FOXP1 and FOXP2 are expressed in songbird and human brain regions that are important for the developmental processes that culminate in speech and language. ©2010 Wiley-Liss, Inc

Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: towards recommendation for molecular testing and management

International audienceSHORT syndrome has historically been defined by its acronym: short stature (S), hyperextensibility of joints and/or inguinal hernia (H), ocular depression (O), Rieger abnormality (R) and teething delay (T). More recently several research groups have identified PIK3R1 mutations as responsible for SHORT syndrome. Knowledge of the molecular etiology of SHORT syndrome has permitted a reassessment of the clinical phenotype. The detailed phenotypes of 32 individuals with SHORT syndrome and PIK3R1 mutation, including eight newly ascertained individuals, were studied to fully define the syndrome and the indications for PIK3R1 testing. The major features described in the SHORT acronym were not universally seen and only half (52%) had 4 or more of the classic features. The commonly observed clinical features of SHORT syndrome seen in the cohort included IUGR \textless 10(th) percentile, postnatal growth restriction, lipoatrophy and the characteristic facial gestalt. Anterior chamber defects and insulin resistance or diabetes were also observed but were not as prevalent. The less specific, or minor features of SHORT syndrome include teething delay, thin wrinkled skin, speech delay, sensorineural deafness, hyperextensibility of joints and inguinal hernia. Given the high risk of diabetes mellitus, regular monitoring of glucose metabolism is warranted. An echocardiogram, ophthalmological and hearing assessments are also recommended

Mutations of AKT3 are associated with a wide spectrum of developmental disorders including extreme megalencephaly

Mutations of genes within the phosphatidylinositol-3-kinase (PI3K)-AKT-MTOR pathway are well known causes of brain overgrowth (megalencephaly) as well as segmental cortical dysplasia (such as hemimegalencephaly, focal cortical dysplasia and polymicrogyria). Mutations of the AKT3 gene have been reported in a few individuals with brain malformations, to date. Therefore, our understanding regarding the clinical and molecular spectrum associated with mutations of this critical gene is limited, with no clear genotype–phenotype correlations. We sought to further delineate this spectrum, study levels of mosaicism and identify genotype–phenotype correlations of AKT3-related disorders. We performed targeted sequencing of AKT3 on individuals with these phenotypes by molecular inversion probes and/or Sanger sequencing to determine the type and level of mosaicism of mutations. We analysed all clinical and brain imaging data of mutation-positive individuals including neuropathological analysis in one instance. We performed ex vivo kinase assays on AKT3 engineered with the patient mutations and examined the phospholipid binding profile of pleckstrin homology domain localizing mutations. We identified 14 new individuals with AKT3 mutations with several phenotypes dependent on the type of mutation and level of mosaicism. Our comprehensive clinical characterization, and review of all previously published patients, broadly segregates individuals with AKT3 mutations into two groups: patients with highly asymmetric cortical dysplasia caused by the common p.E17K mutation, and patients with constitutional AKT3 mutations exhibiting more variable phenotypes including bilateral cortical malformations, polymicrogyria, periventricular nodular heterotopia and diffuse megalencephaly without cortical dysplasia. All mutations increased kinase activity, and pleckstrin homology domain mutants exhibited enhanced phospholipid binding. Overall, our study shows that activating mutations of the critical AKT3 gene are associated with a wide spectrum of brain involvement ranging from focal or segmental brain malformations (such as hemimegalencephaly and polymicrogyria) predominantly due to mosaic AKT3 mutations, to diffuse bilateral cortical malformations, megalencephaly and heterotopia due to constitutional AKT3 mutations. We also provide the first detailed neuropathological examination of a child with extreme megalencephaly due to a constitutional AKT3 mutation. This child has one of the largest documented paediatric brain sizes, to our knowledge. Finally, our data show that constitutional AKT3 mutations are associated with megalencephaly, with or without autism, similar to PTEN-related disorders. Recognition of this broad clinical and molecular spectrum of AKT3 mutations is important for providing early diagnosis and appropriate management of affected individuals, and will facilitate targeted design of future human clinical trials using PI3K-AKT pathway inhibitors

Clinical Presentation of a Complex Neurodevelopmental Disorder Caused by Mutations in ADNP

Background In genome-wide screening studies for de novo mutations underlying autism and intellectual disability, mutations in the ADNP gene are consistently reported among the most frequent. ADNP mutations have been identified in children with autism spectrum disorder comorbid with intellectual disability, distinctive facial features, and deficits in multiple organ systems. However, a comprehensive clinical description of the Helsmoortel-Van der Aa syndrome is lacking. Methods We identified a worldwide cohort of 78 individuals with likely disruptive mutations in ADNP from January 2014 to October 2016 through systematic literature search, by contacting collaborators, and through direct interaction with parents. Clinicians filled in a structured questionnaire on genetic and clinical findings to enable correlations between genotype and phenotype. Clinical photographs and specialist reports were gathered. Parents were interviewed to complement the written questionnaires. Results We report on the detailed clinical characterization of a large cohort of individuals with an ADNP mutation and demonstrate a distinctive combination of clinical features, including mild to severe intellectual disability, autism, severe speech and motor delay, and common facial characteristics. Brain abnormalities, behavioral problems, sleep disturbance, epilepsy, hypotonia, visual problems, congenital heart defects, gastrointestinal problems, short stature, and hormonal deficiencies are common comorbidities. Strikingly, individuals with the recurrent p.Tyr719* mutation were more severely affected. Conclusions This overview defines the full clinical spectrum of individuals with ADNP mutations, a specific autism subtype. We show that individuals with mutations in ADNP have many overlapping clinical features that are distinctive from those of other autism and/or intellectual disability syndromes. In addition, our data show preliminary evidence of a correlation between genotype and phenotype.This work was supported by grants from the European Research Area Networks Network of European Funding for Neuroscience Research through the Research Foundation–Flanders and the Chief Scientist Office–Ministry of Health (to RFK, GV, IG). This research was supported, in part, by grants from the Simons Foundation Autism Research Initiative (Grant No. SFARI 303241 to EEE) and National Institutes of Health (Grant No. R01MH101221 to EEE). This work was also supported by the Italian Ministry of Health and ‘5 per mille’ funding (to CR). For many individuals, sequencing was provided by research initiatives like the Care4Rare Research Consortium in Canada or the Deciphering Developmental Disorders (DDD) study in the UK. The DDD Study presents independent research commissioned by the Health Innovation Challenge Fund (Grant No. HICF-1009–003), a parallel funding partnership between the Wellcome Trust and the Department of Health, and the Wellcome Trust Sanger Institute (Grant No. WT098051). The views expressed in this publication are those of the author(s) and not necessarily those of the Wellcome Trust or the Department of Health. The study has UK Research Ethics Committee approval (10/H0305/83, granted by the Cambridge South Research Ethics Committee, and GEN/284/12 granted by the Republic of Ireland Research Ethics Committee). The research team acknowledges the support of the National Institute for Health Research, through the Comprehensive Clinical Research Network