Temporospatial inhibition of Erk signaling is required for lymphatic valve formation

Intraluminal lymphatic valves(LVs)and lymphovenous valves(LVs)are critical to ensure the unidirectional flow of lymphatic fluid.Morphological abnormalities in these valves always cause lymph or blood reflux,and result in lymphedema.

Preface to the special topic on gene editing towards translation

The first draft of the human genome,published in 2001,has had a broad effect on biomedical studies and applications.In the past two decades,the human genome project(HGP)has dramatically promoted our understanding of how genomic sequences work during development,diseases and evolution.Meanwhile,genome-editing technologies have been rapidly developed to precisely and efficiently rewrite DNA sequences of different species,especially in 2012 as the development of a revolutionary genome editing method based on clustered regularly interspaced short palindromic repeat(CRISPR)and CRISPR-associated(Cas)proteins.

TGFβ1a regulates zebrafish posterior lateral line formation via Smad5 mediated pathway

The zebrafish sensory posterior lateral line(pLL)has become an attractive model for studying collective cell migration and cell morphogenesis.Recent studies have indicated that chemokine,Wnt/β-catenin,Fgf,and Delta-Notch signaling pathways participate in regulating pLL development.However,it remains unclear whether TGFβsignaling pathway is involved in pLL development.Here we report a critical role of TGFβ1 in regulating morphogenesis of the pLL primordium(pLLP).The tgfβ1a gene is abundantly expressed in the lateral line primordium.Knockdown or knockout of tgfβ1a leads to a reduction of neuromast number,an increase of inter-neuromast distance,and a reduced number of hair cells.The aberrant morphogenesis in embryos depleted of tgfβ1a correlates with the reduced expression of atoh1a,deltaA,and n-cadherin/cdh2,which are known important regulators of the pLLP morphogenesis.Like tgfβ1a depletion,knockdown of smad5 that expresses in the pLLP,affects pLLP development whereas overexpression of a constitutive active Smad5 isoform rescues the defects in embryos depleted of tgfβ1a,indicating that Smad5 mediates tgfβ1a function in pLLP development.Therefore,TGFβ/Smad5 signaling plays an important role in the zebrafish lateral line formation.

A harlequin ichthyosis pig model with a novel ABCA12 mutation can be rescued by acitretin treatment

Harlequin ichthyosis (HI) is a severe genetic skin disorder and caused by mutation in the ATP-binding cassette A12 (ABCA12) gene. The retinoid administration has dramatically improved long-term survival of HI, but improvements are still needed. However, the ABCA12 null mice failed to respond to retinoid treatment, which impedes the development of novel cure strategies for HI. Here we generated an ethylnitrosourea mutagenic HI pig model (named Z9), which carries a novel deep intronic mutation IVS49-727 A>G in the ABCA12 gene, resulting in abnormal mRNA splicing and truncated protein production. Z9 pigs exhibit significant clinical symptom as human patients with HI. Most importantly, systemic retinoid treatment significantly prolonged the life span of the mutant pigs via improving epidermal maturation, decreasing epidermal apoptosis, and triggering the expression of ABCA6. Taken together, this pig model perfectly resembles the clinical symptom and molecular pathology of patients with HI and will be useful for understanding mechanistic insight and developing therapeutic strategies.

Induction of cranial and posterior trunk neural crest by exogenous retinoic acid in zebrafish

Retinoic acid (RA) plays an important role in development of vertebrate embryos. We demonstrate impacts of exogenous RA on the formation of neural crest cells in zebrafish using specific neural crest markers sox9b and crestin. Treatment with all-trans RA at 10-7 mmol/L at 50% epiboly induces sox9b expression in the forebrain and crestin expression in the forebrain and midbrain, resulting in significant increase of pigment cells in the head derived from the cranial neural crest. In addition, RA treatment induces expression of sox9b and crestin in the caudal marginal cells of the neuroectoderm during early segmentation. Earlier commitment of these cells to the neural crest fate in the posterior margins leads to abnormal development of the posterior body, probably by preventing mingling of ventral derived and dorsal-derived cells during the formation of the tailbud.

A 2-bp insertion(c.6768insCC) in MC1R causes recessive white coat color in Bama miniature pigs

Coat color is an important characteristic of various breeds of domestic animal species.Variation in farm animal coat color is of considerable interest for concealment,communication and protection against solar radiation（Slominski et al.,2004）.It also plays an important role in the regulation of physiological processes（Miyagi and Terai,2013）.

A zebrafish gene trap line expresses GFP recapturing expression pattern of foxj1b

Foxj1 has been found to play an important role in cilia formation and function in vertebrates. The zebrafish or Xenopus genome expresses two Foxjl genes, foxjlalFoxJ1 and foxjlb/FoxJ1.2. In this study, we have generated a zebrafish transgenic line T2BGSZIO by Tol2 transposon-based gene trapping approach. T2BGSZ10 transgenic fish carry an insertion of the transposon genome into the first intron of thefoxj1b locus. This insertion results in GFP expression in the forebrain, otic vesicles, floorplate, pronephric ducts and other domains during embryogenesis, which recaptures the expression pattern offoxj1b. Although normal expression offoxj1b is dramatically reduced, T2BGSZ10 homozygous embryos develop normally and grow to adulthood without detectable defects, which may be due to the incomplete interruption of foxjlb expression. Nevertheless, this transgenic line may serve as a useful model for dynamic observation of GFP-labeled tissues and organs and for isolation of GFP-labeled cells.

prpf4 is essential for cell survival and posterior lateral line primordium migration in zebrafish

Prpf4 （pre-mRNA processing factor 4）, a key component of spliceosome, plays critical roles in pre-mRNA splicing and its mutations result in retinitis pigmentosa due to photoreceptor defects. In this study, we characterized a zebrafish prpf4t243 mutant harboring a Tol2 transposon-based gene trap cassette in the third intron of the prpf4 gene. Cells in the brain and spinal cord gradually undergo p53-dependent apoptosis after 28 hpf in prpf4t243 mutants, suggesting that a widespread function of prpf4 in neural cell survival. In addition, prpf4 is essential for survival of posterior lateral line primordial （pLLP） cells, prpf4 deficiency perturbs Fgf, Wnt/β-catenin and chemokine signaling pathways and impairs pLLP migration. RNA-Seq analysis suggests that prpf4 deficiency may impair spliceosome assembly, leading to compensatory upregulation of core spliceosomal genes and alteration of pre-mRNA splicing. Taken together, our studies uncover an essential role of prpf4 in pre-mRNA splicing, cell survival and pLLP migration.

The rising zebrafish research in China：Meeting report of the 3rd Chinese Zebrafish Principal Investigator Meeting ＆ the Inaugural Meeting of China Zebrafish Society

The zebrafish has become a very important animal model,not only for developmental biology and genetics,but also for disease modeling and drug discovery.Since the year of 2000,zebrafish research has been rapidly growing in China,and the laboratories using zebrafish as the main subject have been increasing dramatically（Xie et al.,2015）.For example,the number of participants who attended the Chinese Zebrafish Principle Investigator （PI） Meeting series is 80 in 2012, 150 in 2014, and over 200 this year.

Understanding recurrent pregnancy loss:recent advances on its etiology,clinical diagnosis,and management

Recurrent pregnancy loss(RPL)has become an important reproductive health issue worldwide.RPL affects about 2%–3%of reproductive-aged women,and makes serious threats to women’s physical and mental health.However,the etiology of approximately 50%of RPL cases remains unknown(unexplained RPL),which poses a big challenge for clinical management of these patients.RPL has been widely regarded as a complex disease where its etiology has been attributed to numerous factors.Heretofore,various risk factors for RPL have been identified,such as maternal ages,genetic factors,anatomical structural abnormalities,endocrine dysfunction,prethrombotic state,immunological factors,and infection.More importantly,development and applications of next generation sequencing technology have significantly expanded opportunities to discover chromosomal aberrations and single gene variants responsible for RPL,which provides new insight into its pathogenic mechanisms.Furthermore,based upon patients’diagnostic evaluation and etiologic diagnosis,specific therapeutic recommendations have been established.This review will highlight current understanding and recent advances on RPL,with a special focus on the immunological and genetic etiologies,clinical diagnosis and therapeutic management.

The Tiny Zebrafish Keep Swimming Fast in the Developmental Biology Pond

In 1996,the journal Development published a special issue on zebrafish solely focusing on characterization of dozens of phenotypic mutants chosen from hundreds of mutants identified through chemical（ENU）mutagenesis by two zebrafish groups in Tubingen and Boston.This milestone formally catapulted zebrafish to a league of genetically tractable model

The genetic program Of oocytes can be modified in vivo in the zebrafish ovary

Oocytes,the irreplaceable gametes for generating a new organism,are matured in the ovary of living female animals.It is unknown whether any genetic manipulations can be applied to immature oocytes inside the living ovaries.As a proof-of-concept, we here demonstrate genetic amendments of zebrafish immature oocytes within the ovary.Oocyte microinjection in situ (OMIS) stimulates tissue repair responses,but some of the microinjected immature oocytes are matured,ovulated and fertilizable.By OMIS-mediated Cas9 approach,ntla and gata5 loci of oocytes arrested at prophase I of meiosis are successfully edited before fertilization.Through OMIS,high efficiency of biaUeUc mutations in single or multiple loci using Cas9/gRNAs allows immediate manifestation of mutant phenotypes in Fo embryos and multiple transgenes can co-express the reporters in Fo embryos with patterns similar to germline transgenic embryos.Furthermore,maternal knockdown of dnmt1 by antisense morphoino via OMIS results in a dramatic decrease of global DNA methylation level at the dome stage and causes embryonic lethalityprior to segmentation period.Therefore,OMIS opens a door to efficiently modify the genome and provides a possibility to re repair genetically abnormal oocytes in situ.

Aagab is required for zebrafish larval development by regulating neural activity

Clathrin-mediated endocytosis has been implicated in various physiological processes,including nutrient uptake,signal transduction,synaptic vesicle recycling,maintenance of cell polarity,and antigen presentation.Despite prior knowledge of its importance as a key regulator in promoting clathrin-mediated endocytosis,the physiological function of α-and γ-adaptin binding protein(aagab)remains elusive.In this study,we investigate the biological function of aagab during zebrafish development.We establish a loss-of-function mutant of aagab in zebrafish,revealing impaired swimming and early larval mortality.Given the high expression level of aagab in the brain,we probe into its physiological role in the nervous system.aagab mutants display subdued calcium responses and local field potential in the optic tectal neurons,aligning with reduced neurotransmitter release(e.g.,norepinephrine)in the tectal neuropil of aagab mutants.Overexpressing aagab mRNA or nervous stimulant treatment in mutants restores neurotransmitter release,calcium responses,swimming ability,and survival.Furthermore,our observations show delayed release of FM 1-43 in AAGAB knockdown differentiated neuroblastoma cells,pointing towards a probable link to defective clathrin-mediated synaptic vesicle recycling.In conclusion,our study underscores the significance of Aagab in neurobiology and suggests its potential impacts on neurological disorders.