HS-10352 in hormone receptor-positive, HER2-negative advanced breast cancer: A phase 1 dose-escalation trial.

BACKGROUND: Approximately 40% of patients with hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer (ABC) exhibit PIK3CA mutations. AIMS: This study aims to evaluate the safety, tolerability, pharmacokinetics, and preliminary antitumor activity of HS-10352, a selective PI3Kα inhibitor, in this patient population. MATERIALS AND METHODS: Conducted as a phase 1 dose-escalation trial, HS-10352 was administered orally once-daily (QD) at dose levels of 2, 4, 6, and 8 mg. The primary endpoints were dose-limiting toxicity (DLT) and the maximum tolerated dose (MTD). This study is registered at ClinicalTrials.gov (NCT04631835). RESULTS: Between August 2020 and March 2022, a total of 18 female patients were enrolled. DLT, manifested as hyperglycemia, occurred in two patients in the 8 mg QD group, establishing an MTD of 6 mg QD. The most common treatment-related adverse events were hyperglycemia (88.9%) and weight loss (61.3%). In the 6 mg QD group, four patients (66.7%) had a partial response (PR), and one (16.7%) had stable disease (SD). Among the four patients with PIK3CA mutated tumors in this dosage group, three (75.0%) had PR and one (25.0%) had SD. The median progression-free survival was not reached (95% confidence interval, 11.1-NA). DISCUSSION AND CONCLUSION: HS-10352 at 6 mg QD was well-tolerated in patients with HR-positive, HER2-negative ABC, and showed preliminary antitumor activity in patients with PIK3CA mutated tumors. These findings support the further clinical development of HS-10352.

Analysis of clinical characteristics and treatment efficacy in two pediatric cases of ANKRD26-related thrombocytopenia.

ANKRD26-related thrombocytopenia (ANKRD26-RT or THC2, MIM 188 000), an autosomal dominant thrombocytopenia, is unresponsive to immunosuppressive therapy and susceptible to hematological malignancies. A large number of pediatric patients are diagnosed with immune thrombocytopenia (ITP) every year; however, thrombocytopenia of genetic origin is often missed. Extensive characterization of ANKRD26-RT will help prevent missed diagnosis and misdiagnosis. Furthermore, identification of ANKRD26-RT will help in the formulation of an accurate diagnosis and a treatment plan. In our study, we report cases of two Chinese pediatric patients with ANKRD26-RT and analyze their clinical characteristics, gene mutations, and treatment modalities. Both patients were 1-year-old and presented with mild bleeding (World Health Organization(WHO) score grade 1), different degrees of platelet reduction, normal mean platelet volume, and megakaryocyte maturation impairment not obvious. Genetic tests revealed that both patients had ANKRD26 gene mutations.Patient 1 had a mutation c.-140C>G of the 5' untranslated region (UTR), and patient 2 had a mutation of c.-127A>T of 5'UTR. Both patients were treated with eltrombopag, and the treatment was no response, with no adverse reactions.

What is the background? ANKRD26-RT is an autosomal dominant thrombocytopenia which is unresponsive to immunosuppressive therapy and susceptible to hematological malignancies.It is rare and lacks specific clinical features, making misdiagnosis easy.Some studies report that eltrombopag is safe and effective for short-term treatment of the disease; however, these reports are limited.What we did and summary of findings. We retrospectively studied the clinical manifestations and diagnosis process of ANKRD26-RT and discussed the treatment efficacy of immunosuppressants and eltrombopag for its management.We found two pediatric cases of patients with ANKRD26-RT with varying degrees of thrombocytopenia, mild bleeding, normal mean platelet volume, and megakaryocyte maturation impairment that was not obvious. Immunosuppressant treatment wasunresponsiveor temporarily responsivebut not sustained , and short-term administration of eltrombopag (25 mg/day) was safe, but it did not effectively improve the patients' platelet counts.What is the impact? If patients clinically diagnosed with immune thrombocytopenia do not respond  to immunosuppressive agents, genetic testing should be conducted to exclude hereditary thrombocytopenia, and a normal mean platelet volume should not exclude the possibility of the disease.For patients with ANKRD26-RT, eltrombopag is safe for short-term use;however, 25 mg/day treatment is unresponsive.Ourreport complements data on the diagnosis and management of ANKRD26-RT disease in children.

Corrigendum: High expression level of the FTH1 gene is associated with poor prognosis in children with non-M3 acute myeloid leukemia.

[This corrects the article DOI: 10.3389/fonc.2022.1068094.].

Ionizing radiation alters functional neurotransmission in Drosophila larvae.

Introduction: Patients undergoing cranial ionizing radiation therapy for brain malignancies are at increased risk of long-term neurocognitive decline, which is poorly understood and currently untreatable. Although the molecular pathogenesis has been intensively researched in many organisms, whether and how ionizing radiation alters functional neurotransmission remains unknown. This is the first study addressing physiological changes in neurotransmission after ionizing radiation exposure. Methods: To elucidate the cellular mechanisms of radiation damage, using calcium imaging, we analyzed the effects of ionizing radiation on the neurotransmitter-evoked responses of prothoracicotropic hormone (PTTH)-releasing neurons in Drosophila larvae, which play essential roles in normal larval development. Results: The neurotransmitters dopamine and tyramine decreased intracellular calcium levels of PTTH neurons in a dose-dependent manner. In gamma irradiated third-instar larvae, a dose of 25 Gy increased the sensitivity of PTTH neurons to dopamine and tyramine, and delayed development, possibly in response to abnormal functional neurotransmission. This irradiation level did not affect the viability and arborization of PTTH neurons and successful survival to adulthood. Exposure to a 40-Gy dose of gamma irradiation decreased the neurotransmitter sensitivity, physiological viability and axo-dendritic length of PTTH neurons. These serious damages led to substantial developmental delays and a precipitous reduction in the percentage of larvae that survived to adulthood. Our results demonstrate that gamma irradiation alters neurotransmitter-evoked responses, indicating synapses are vulnerable targets of ionizing radiation. Discussion: The current study provides new insights into ionizing radiation-induced disruption of physiological neurotransmitter signaling, which should be considered in preventive therapeutic interventions to reduce risks of neurological deficits after photon therapy.

A Visual Pathway into Central Complex for High-Frequency Motion-Defined Bars in Drosophila.

Relative motion breaks a camouflaged target from a same-textured background, thus eliciting discrimination of a motion-defined object. Ring (R) neurons are critical components in the Drosophila central complex, which has been implicated in multiple visually guided behaviors. Using two-photon calcium imaging with female flies, we demonstrated that a specific population of R neurons that innervate the superior domain of bulb neuropil, termed superior R neurons, encoded a motion-defined bar with high spatial frequency contents. Upstream superior tuberculo-bulbar (TuBu) neurons transmitted visual signals by releasing acetylcholine within synapses connected with superior R neurons. Blocking TuBu or R neurons impaired tracking performance of the bar, which reveals their importance in motion-defined feature encoding. Additionally, the presentation of a low spatial frequency luminance-defined bar evoked consistent excitation in R neurons of the superior bulb, whereas either excited or inhibited responses were evoked in the inferior bulb. The distinct properties of the responses to the two bar stimuli indicate there is a functional division between the bulb subdomains. Moreover, physiological and behavioral tests with restricted lines suggest that R4d neurons play a vital role in tracking motion-defined bars. We conclude that the central complex receives the motion-defined features via a visual pathway from superior TuBu to R neurons and might encode different visual features via distinct response patterns at the population level, thereby driving visually guided behaviors.SIGNIFICANCE STATEMENT Animals could discriminate a motion-defined object that is indistinguishable with a same-textured background until it moves, but little is known about the underlying neural mechanisms. In this study, we identified that R neurons and their upstream partners, TuBu neurons, innervating the superior bulb of Drosophila central brain are involved in the discrimination of high-frequency motion-defined bars. Our study provides new evidence that R neurons receive multiple visual inputs from distinct upstream neurons, indicating a population coding mechanism for the fly central brain to discriminate diverse visual features. These results build progress in unraveling neural substrates for visually guided behaviors.

Structural and functional characterization of novel F7 mutations identified in Chinese factor VII-deficient patients.

Hereditary factor VII (FVII) deficiency is a rare recessive bleeding disorder with an estimated prevalence of 1/500 000. We had investigated 50 unrelated Chinese patients with FVII deficiency and identified, in total, 25 mutations, including 18 missense mutations and 5 splicing mutations, on the F7 gene. The nucleotide transition c.1224T>G (p.His408Gln) in exon 9 constitutes a hotspot of mutation, with 19 patients harbouring this genetic variance. Few patients were homozygous or compound heterozygous for deleterious mutations, such as non-sense mutations, large insertion or deletions, indicating that complete deficiency of FVII may not be compatible with life. The eight novel mutations identified in the study, including one small deletion (p.Glu49GlyfsTer101), three type I missense mutations, p.Cys238Phe, p.Gly420Asp, p.Ala252Val and four type II missense mutations, p.Val336Met, p.Ser342Gly, p.Gly432Ser and p.Ile213Asn, were further analysed by in vitro expression and functional studies. The laboratory phenotype and structural analysis confirmed the functional consequence of p.Ile213Asn mutation involving cleavage and activation site. The molecular dynamic simulations and binding energy calculations along with functional probing of p.Gly432Ser mutation revealed the critical role of residue Gly432 in the binding between activated factor VII (factor VIIa) and tissue factor.

A remarkably diverse and well-organized virus community in a filter-feeding oyster.

BACKGROUND: Viruses play critical roles in the marine environment because of their interactions with an extremely broad range of potential hosts. Many studies of viruses in seawater have been published, but viruses that inhabit marine animals have been largely neglected. Oysters are keystone species in coastal ecosystems, yet as filter-feeding bivalves with very large roosting numbers and species co-habitation, it is not clear what role they play in marine virus transmission and coastal microbiome regulation. RESULTS: Here, we report a Dataset of Oyster Virome (DOV) that contains 728,784 nonredundant viral operational taxonomic unit contigs (≥ 800 bp) and 3473 high-quality viral genomes, enabling the first comprehensive overview of both DNA and RNA viral communities in the oyster Crassostrea hongkongensis. We discovered tremendous diversity among novel viruses that inhabit this oyster using multiple approaches, including reads recruitment, viral operational taxonomic units, and high-quality virus genomes. Our results show that these viruses are very different from viruses in the oceans or other habitats. In particular, the high diversity of novel circoviruses that we found in the oysters indicates that oysters may be potential hotspots for circoviruses. Notably, the viruses that were enriched in oysters are not random but are well-organized communities that can respond to changes in the health state of the host and the external environment at both compositional and functional levels. CONCLUSIONS: In this study, we generated a first "knowledge landscape" of the oyster virome, which has increased the number of known oyster-related viruses by tens of thousands. Our results suggest that oysters provide a unique habitat that is different from that of seawater, and highlight the importance of filter-feeding bivalves for marine virus exploration as well as their essential but still invisible roles in regulating marine ecosystems. Video Abstract.

[Genetic Analysis and Prenatal Diagnosis of a Family with Hereditary Spherocytosis Caused by a Novel Compound Heterozygous Mutation of SPTB Gene].

OBJECTIVE: To investigate the clinical and genetic characteristics of a family with hereditary spherocytosis (HS), to clarify the cause of the disease, and to provide the basis for genetic counseling and prenatal diagnosis. METHODS: The clinical data of proband and his parents were collected, and HS-related pathogenic genovariation of the proband was detected by high throughput sequencing. Suspected pathogenic mutation sites were verified by PCR-Sanger sequencing, and the fetus were conceived by a proband mother underwent prenatal diagnosis. RESULTS: Clinical manifestations of the proband showed moderate anemia, mild splenomegaly, and jaundice (an indirect increase of bilirubin). The gene detection showed that the proband showed compound heterozygous mutations of SPTB gene c. 6095T > C (p.Leu2032Pro) and c. 6224A > G (p.Glu2075Gly), which was inherited from the asymptomatic mother and father, respectively. Both mutations were detected rarely in the common population. Prenatal diagnosis revealed that the fetus inherited a mutant gene of the mother. CONCLUSION: The compound heterozygous mutations of SPTB genes c.6095T>C (p.Leu2032Pro) and c.6224A>G (p.Glu2075Gly) were the causes of the family disease, which provides a basis for family genetic counseling and prenatal diagnosis. This report is the first one found in the HGMD,1000G and EXAC database, which provides an addition to the mutation profile of the SPTB gene.

Clinical and molecular characteristics of Wiskott-Aldrich Syndrome in five unrelated Chinese families.

Wiskott-Aldrich syndrome (WAS) also called the eczema-thrombocytopenia-immunodeficiency syndrome is a primary immunodeficiency disease with X-linked recessive inheritance caused by mutations in the WAS protein (WASp) gene and characterized by thrombocytopenia with reduced platelet volume, eczema, immunodeficiency, and increased risk of malignant tumours. The mutations will lead to separate WAS severity which can be typical severe 'classical' WAS or less severe 'non-classical' WAS. This article will review and analyse clinical and immune characteristics of five unrelated Chinese families harbouring classical and non-classical WAS. The expression of WASp was detected in the peripheral blood monocytes (PBMC) by flow cytometry, and five mutations were found by WAS gene sequencing, one of which had not been reported in the literature, namely frameshift mutation c.1240_1247delCCACTCCC (p. P414Sfs*41).

Efficacy of Aumolertinib (HS-10296) in Patients With Advanced EGFR T790M+ NSCLC: Updated Post-National Medical Products Administration Approval Results From the APOLLO Registrational Trial.

INTRODUCTION: Aumolertinib (formerly almonertinib; HS-10296) is a novel third-generation EGFR tyrosine kinase inhibitor (TKI) with revealed activity against EGFR-sensitizing mutations and EGFR T790M mutation. METHODS: Patients with locally advanced or metastatic NSCLC who developed an EGFR T790M mutation after progression on first- or second-generation EGFR TKI therapy were enrolled in this registrational phase 2 trial of aumolertinib at 110 mg orally once daily (NCT02981108). The primary end point was objective response rate (ORR) by independent central review. RESULTS: A total of 244 patients with EGFR T790M-positive NSCLC were enrolled. The ORR by independent central review was 68.9% (95% confidence interval [CI]: 62.6-74.6). The disease control rate was 93.4% (95% CI: 89.6-96.2). The median duration of response was 15.1 months (95% CI: 12.5-16.6). The median progression-free survival was 12.4 months (95% CI: 9.7-15.0). Among 23 patients with assessable central nervous system (CNS) metastases, the CNS-ORR and CNS-disease control rate were 60.9% (95% CI: 38.5-80.3) and 91.3% (95% CI: 72.0-98.9), respectively. The median CNS-duration of response was 12.5 months (95% CI: 5.6-not reached). Treatment-related adverse events of more than or equal to grade 3 occurred in 16.4% of the patients, with the most common being increased blood creatine phosphokinase level (7%) and increased alanine aminotransferase level (1.2%). The relative dose density of aumolertinib was 99.2% in this study. CONCLUSIONS: Aumolertinib is an effective and well-tolerated third-generation EGFR TKI for patients with EGFR T790M-positive advanced NSCLC after disease progression on first- and second-generation EGFR TKI therapy. On the basis of these findings, aumolertinib was approved in the People's Republic of China for patients positive for EGFR T790M NSCLC.

High expression level of the FTH1 gene is associated with poor prognosis in children with non-M3 acute myeloid leukemia.

Acute myelogenous leukemia (AML) is a disease that severely affects the physical health of children. Thus, we aimed to identify biomarkers associated with AML prognosis in children. Using transcriptomics on an mRNA dataset from 27 children with non-M3 AML, we selected genes from among those with the top 5000 median absolute deviation (MAD) values for subsequent analysis which showed that two modules were associated with AML risk groups. Thus, enrichment analysis was performed using genes from these modules. A one-way Cox analysis was performed on a dataset of 149 non-M3 AML patients downloaded from the TCGA. This identified four genes as significant: FTH1, RCC2, ABHD17B, and IRAK1. Through survival analysis, FTH1 was identified as a key gene associated with AML prognosis. We verified the proliferative and regulatory effects of ferroptosis on MOLM-13 and THP-1 cells using Liproxstatin-1 and Erastin respectively by CCK-8 and flow cytometry assays. Furthermore, we assayed expression levels of FTH1 in MOLM-13 and THP-1 cells after induction and inhibition of ferroptosis by real-time quantitative PCR, which showed that upregulated FTH1 expression promoted proliferation and inhibited apoptosis in leukemia cells. In conclusion, high expression of FTH1 promoted proliferation and inhibited apoptosis of leukemic cells through the ferroptosis pathway and is thus a potential risk factor that affects the prognosis of non-M3 AML in children.

Identification of two novel mutations in three children with congenital factor VII deficiency.

Congenital factor VII deficiency (FVIID) is a rare F7 gene mutation causing bleeding disorder inherited in an autosomal recessive manner. In this study, we aimed to identify genetic defects and analyze their relationships with phenotype in three Chinese FVIID patients. The diagnosis of FVIID was made based on FVII coagulant activity (FVII:C) levels assessed through prothrombin time assay. Direct sequencing and protein modeling were performed to detect genetic mutations and the resulting protein expression. Patient 1, a 2-year-old girl, presented with mild bleeding and was found to have a FVII:C of 0.2% and a compound heterozygous F7 Cys389Gly/Cys115Arg mutation. Patient 2, a 7-year-old boy, consulted for moderate bleeding and was found to have a FVII:C of 0.8% and a compound heterozygous F7 Thr241Asn/Pro324Leu mutation. Patient 3, a 5-year-old boy who developed a mild bleeding after trauma was found to have a FVII:C of 1.8% and a compound heterozygous F7 Thr241Asn/ IVS5-2A>G mutation. We hereby report three congenital FVIID patients with FVII:C less than 2% and their respective F7 mutations, two of which (F7 Cys115Arg, Pro324Leu) are novel. The molecular model analysis of the two novel mutations F7 Cys115Arg and Pro324Leu respectively indicated impairment of the proper folding of epidermal growth factor 1 domain situated on F7 gene and impairment of the procoagulant function of FVII both leading to the congenital deficiency of FVII.

Spectrum of ß-Thalassemia Mutations in Some Areas of Guangxi Zhuang Autonomous Region of Southern China: A Study on a Pediatric Population Aged 0-15 Years.

ß-Thalassemia (ß-thal), one of the most common form of single-gene inheritable blood diseases in the world, is highly prevalent in southern China, especially in the Guangxi Zhuang Autonomous Region. To update the ß-thal mutation spectrum in this region, we performed hematological and genetic analyses on 888 ß-thal major (ß-TM), ß-thal intermedia (ß-TI) and ß-thal carrier patients, aged 0-15 years old, from different parts of Guangxi Province. We identified 55 genotypes and 18 ß-thal mutations. The codons 41/42 (-TTCT) (HBB: c.126_129delCTTT) (43.97%), codon 17 (A>T) (HBB: c.52A>T) (25.43%), -28(A>G) (HBB: c.-78A>G) (8.18%), IVS-II-654 (C>T) (HBB: c.316-197C>T) (7.85%) and codon 26 (G>A) (HBB: c.79G>A) (5.02%) were the five most common, accounting for more than 90.0%. The results of our study are providing an up-to-date ß-thal mutation spectrum in the 0-15-year-old pediatric population, which will help genetic counseling and prevention of ß-TM in mainland China's most endemic region, Guangxi Zhuang Autonomous Region.

Neurotransmitters Affect Larval Development by Regulating the Activity of Prothoracicotropic Hormone-Releasing Neurons in Drosophila melanogaster.

Ecdysone, an essential insect steroid hormone, promotes larval metamorphosis by coordinating growth and maturation. In Drosophila melanogaster, prothoracicotropic hormone (PTTH)-releasing neurons are considered to be the primary promoting factor in ecdysone biosynthesis. Recently, studies have reported that the regulatory mechanisms of PTTH release in Drosophila larvae are controlled by different neuropeptides, including allatostatin A and corazonin. However, it remains unclear whether neurotransmitters provide input to PTTH neurons and control the metamorphosis in Drosophila larvae. Here, we report that the neurotransmitters acetylcholine (ACh) affect larval development by modulating the activity of PTTH neurons. By downregulating the expression of different subunits of nicotinic ACh receptors in PTTH neurons, pupal volume was significantly increased, whereas pupariation timing was relatively unchanged. We also identified that PTTH neurons were excited by ACh application ex vivo in a dose-dependent manner via ionotropic nicotinic ACh receptors. Moreover, in our Ca2+ imaging experiments, relatively low doses of OA caused increased Ca2+ levels in PTTH neurons, whereas higher doses led to decreased Ca2+ levels. We also demonstrated that a low dose of OA was conveyed through OA ß-type receptors. Additionally, our electrophysiological experiments revealed that PTTH neurons produced spontaneous activity in vivo, which provides the possibility of the bidirectional regulation, coming from neurons upstream of PTTH cells in Drosophila larvae. In summary, our findings indicate that several different neurotransmitters are involved in the regulation of larval metamorphosis by altering the activity of PTTH neurons in Drosophila.

Lamina feedback neurons regulate the bandpass property of the flicker-induced orientation response in Drosophila.

Natural scenes contain complex visual cues with specific features, including color, motion, flicker, and position. It is critical to understand how different visual features are processed at the early stages of visual perception to elicit appropriate cellular responses, and even behavioral output. Here, we studied the visual orientation response induced by flickering stripes in a novel behavioral paradigm in Drosophila melanogaster. We found that free walking flies exhibited bandpass orientation response to flickering stripes of different frequencies. The most sensitive frequency spectrum was confined to low frequencies of 2-4 Hz. Through genetic silencing, we showed that lamina L1 and L2 neurons, which receive visual inputs from R1 to R6 neurons, were the main components in mediating flicker-induced orientation behavior. Moreover, specific blocking of different types of lamina feedback neurons Lawf1, Lawf2, C2, C3, and T1 modulated orientation responses to flickering stripes of particular frequencies, suggesting that bandpass orientation response was generated through cooperative modulation of lamina feedback neurons. Furthermore, we found that lamina feedback neurons Lawf1 were glutamatergic. Thermal activation of Lawf1 neurons could suppress neural activities in L1 and L2 neurons, which could be blocked by the glutamate-gated chloride channel inhibitor picrotoxin (PTX). In summary, lamina monopolar neurons L1 and L2 are the primary components in mediating flicker-induced orientation response. Meanwhile, lamina feedback neurons cooperatively modulate the orientation response in a frequency-dependent way, which might be achieved through modulating neural activities of L1 and L2 neurons.

Minimal Essential Human Factor VIII Alterations Enhance Secretion and Gene Therapy Efficiency.

One important limitation for achieving therapeutic expression of human factor VIII (FVIII) in hemophilia A gene therapy is inefficient secretion of the FVIII protein. Substitution of five amino acids in the A1 domain of human FVIII with the corresponding porcine FVIII residues generated a secretion-enhanced human FVIII variant termed B-domain-deleted (BDD)-FVIII-X5 that resulted in 8-fold higher FVIII activity levels in the supernatant of an in vitro cell-based assay system than seen with unmodified human BDD-FVIII. Analysis of purified recombinant BDD-FVIII-X5 and BDD-FVIII revealed similar specific activities for both proteins, indicating that the effect of the X5 alteration is confined to increased FVIII secretion. Intravenous delivery in FVIII-deficient mice of liver-targeted adeno-associated virus (AAV) vectors designed to express BDD-FVIII-X5 or BDD-FVIII achieved substantially higher plasma FVIII activity levels for BDD-FVIII-X5, even when highly efficient codon-optimized F8 nucleotide sequences were employed. A comprehensive immunogenicity assessment using in vitro stimulation assays and various in vivo preclinical models of hemophilia A demonstrated that the BDD-FVIII-X5 variant does not exhibit an increased immunogenicity risk compared to BDD-FVIII. In conclusion, BDD-FVIII-X5 is an effective FVIII variant molecule that can be further developed for use in gene- and protein-based therapeutics for patients with hemophilia A.

Differentiation of Theta Visual Motion from Fourier Motion Requires LC16 and R18C12 Neurons in Drosophila.

Many animals perceive features of higher-order visual motion that are beyond the spatiotemporal correlations of luminance defined in first-order motion. Although the neural mechanisms of first-order motion detection have become understood in recent years, those underlying higher-order motion perception remain unclear. Here, we established a paradigm to assess the detection of theta motion-a type of higher-order motion-in freely walking Drosophila. Behavioral screening using this paradigm identified two clusters of neurons in the central brain, designated as R18C12, which were required for perception of theta motion but not for first-order motion. Furthermore, theta motion-activated R18C12 neurons were structurally and functionally located downstream of visual projection neurons in lobula, lobula columnar cells LC16, which activated R18C12 neurons via interactions of acetylcholine (ACh) and muscarinic acetylcholine receptors (mAChRs). The current study provides new insights into LC neurons and the neuronal mechanisms underlying visual information processing in complex natural scenes.

Circadian pacemaker neurons of the Madeira cockroach are inhibited and activated by GABAA and GABAB receptors.

GABA is the most abundant neurotransmitter in the circadian pacemaker circuits of mammals and insects. In the Madeira cockroach the accessory medulla (AME) in the brain's optic lobes is the circadian clock that orchestrates rest-activity rhythms in synchrony with light dark cycles. Three prominent GABAergic tracts connect the AME to termination sites of compound eye photoreceptors in the lamina and medulla. Parallel GABAergic light entrainment pathways were suggested to either advance or delay the clock for adjustment to changing photoperiods. In agreement with this hypothesis GABA activated or inhibited AME clock neurons, allowing for the distinction of three different GABA response types. Here, we examined which GABA receptors are responsible for these response types. We found that both ionotropic GABAA receptors and metabotropic GABAB receptors were expressed in AME clock cells. Via different signalling pathways, either one of them could account for all three GABA response types. The muscimol-dependently activated GABAA receptor formed a chloride channel, while the SKF 97541-dependently activated GABAB receptor signalled via G-proteins, apparently targeting potassium channels. Expression of chloride exporters or importers determined whether GABAA receptor activation hyper- or depolarized AME neurons. For GABAB receptor responses second messenger gated channels present in the clock cells appeared to decide about the polarity of the GABA response. In summary, circadian clock neurons co-expressed inhibitory and/or excitatory GABAA and GABAB receptors in various combinations, while cotransporter expression and the set of second messenger gated ion channels present allowed for distinct signalling in different clock neurons.