http://www.biomedcentral.com/bmcdevbiol/ The latest research articles published by BMC Developmental Biology 2009-07-08T00:00:00Z This is an RSS newsfeed from BioMed Central It is intended to be used with an RSS reader. For more information about RSS newsfeeds from BioMed Central, visit http://www.biomedcentral.com/info/about/rss/ Background: The condensation of chromosomes and correct sister chromatid segregation during cell division is an essential feature of all proliferative cells. Structural maintenance of chromosomes (SMC) and non-SMC proteins form the condensin I complex and regulate chromosome condensation and segregation during mitosis. However, due to the lack of appropriate mutants, the function of the condensin I complex during vertebrate development has not been described. Results: Here, we report the positional cloning and detailed characterization of retinal phenotypes of a zebrafish mutation at the cap-g locus. High resolution live imaging reveals that the progression of mitosis between prometa- to telophase is delayed and that sister chromatid segregation is impaired upon loss of CAP-G. CAP-G associates with chromosomes between prometa- and telophase of the cell cycle. Loss of the interaction partners CAP-H and CAP-D2 causes cytoplasmic mislocalization of CAP-G throughout mitosis. DNA content analysis reveals increased genomic imbalances upon loss of non-SMC condensin I subunits. Within the retina, loss of condensin I function causes increased rates of apoptosis among cells within the proliferative ciliary marginal zone (CMZ) whereas postmitotic retinal cells are viable. Inhibition of p53-mediated apoptosis partially rescues cell numbers in cap-g mutant retinae and allows normal layering of retinal cell types without alleviating their aberrant nuclear sizes. Conclusions: Our findings indicate that the condensin I complex is particularly important within rapidly amplifying progenitor cell populations to ensure faithful chromosome segregation. In contrast, differentiation of postmitotic retinal cells is not impaired upon polyploidization. http://www.biomedcentral.com/1471-213X/9/40 Sabine Seipold Florian Priller Paul Goldsmith William Harris Herwig Baier Salim Abdelilah-Seyfried BMC Developmental Biology 2009, 9:40 2009-07-08T00:00:00Z doi:10.1186/1471-213X-9-40 BMC Developmental Biology 1471-213X 9 40 2009-07-08T00:00:00Z PDF Background: Creatine synthesis takes place predominately in the kidney and liver via a two-step process involving AGAT (L-arginine:glycine amidinotransferase) and GAMT (guanidinoacetate methyltransferase). Creatine is taken into cells via the creatine transporter (CrT), where it plays an essential role in energy homeostasis, particularly for tissues with high and fluctuating energy demands. Very little is known of the fetal requirement for creatine and how this may change with advancing pregnancy and into the early neonatal period. Using the spiny mouse as a model of human perinatal development, the purpose of the present study was to comprehensively examine the development of the creatine synthesis and transport systems. Results: The estimated amount of total creatine in the placenta and brain significantly increased in the second half of pregnancy, coinciding with a significant increase in expression of CrT mRNA. In the fetal brain, mRNA expression of AGAT increased steadily across the second half of pregnancy, although GAMT mRNA expression was relatively low until 34 days gestation (term is 38-39 days). In the fetal kidney and liver, AGAT and GAMT mRNA and protein expression were also relatively low until 34-37 days gestation. Between mid-gestation and term, neither AGAT or GAMT mRNA or protein could be detected in the placenta. Conclusions: Our results suggest that in the spiny mouse, a species where, like the human, considerable organogenesis occurs before birth, there appears to be a limited capacity for endogenous creatine synthesis until approximately 0.9 of pregnancy. This implies that a maternal source of creatine, transferred across the placenta, may be essential until the creatine synthesis and transport system matures in preparation for birth. If these results also apply to the human, premature birth may increase the risk of creatine deficiency. http://www.biomedcentral.com/1471-213X/9/39 Zoe Ireland Aaron Russell Theo Wallimann David Walker Rod Snow BMC Developmental Biology 2009, 9:39 2009-07-01T00:00:00Z doi:10.1186/1471-213X-9-39 BMC Developmental Biology 1471-213X 9 39 2009-07-01T00:00:00Z PDF Background: Life-long production of spermatozoa depends on spermatogonial stem cells. Spermatogonial stem cells exist among the most primitive population of germ cells - undifferentiated spermatogonia. Transplantation experiments have demonstrated the functional heterogeneity of undifferentiated spermatogonia. Although the undifferentiated spermatogonia can be topographically divided into As (single), Apr (paired), and Aal (aligned) spermatogonia, subdivision of this primitive cell population using cytological markers would greatly facilitate characterization of their functions. Results: In the present study, we show that LIN28, a pluripotency factor, is specifically expressed in undifferentiated spermatogonia (As, Apr, and Aal) in mouse. Ngn3 also specifically labels undifferentiated spermatogonia. We used Ngn3-GFP knockin mice, in which GFP expression is under the control of all Ngn3 transcription regulatory elements. Remarkably, Ngn3-GFP is only expressed in ~40% of LIN28-positive As (single) cells. The percentage of Ngn3-GFP-positive clusters increases dramatically with the chain length of interconnected spermatogonia. Conclusion: Our study demonstrates that LIN28 specifically marks undifferentiated spermatogonia in mice. These data, together with previous studies, suggest that the LIN28-expressing undifferentiated spermatogonia exist as two subpopulations: Ngn3-GFP-negative (high stem cell potential) and Ngn3-GFP-positive (high differentiation commitment). Furthermore, Ngn3-GFP-negative cells are found in chains of Ngn3-GFP-positive spermatogonia, suggesting that cells in the Aal spermatogonia could revert to a more primitive state. http://www.biomedcentral.com/1471-213X/9/38 Ke Zheng Xin Wu Klaus Kaestner Peijing Jeremy Wang BMC Developmental Biology 2009, 9:38 2009-06-29T00:00:00Z doi:10.1186/1471-213X-9-38 BMC Developmental Biology 1471-213X 9 38 2009-06-29T00:00:00Z PDF Background: Fluorescent proteins such as the green fluorescent protein (GFP) have widely been used in transgenic animals as reporter genes. Their use in transgenic Xenopus tadpoles is especially of interest, because large numbers of living animals can easily be screened. To track more than one event in the same animal, fluorescent markers that clearly differ in their emission spectrum are needed. Results: We established the transgenic Xenopus laevis strain tom3 that expresses ubiquitously red fluorescence from the tdTomato gene through all larval stages and in the adult animal. This new tool was applied to track transplanted blastemas obtained after tail amputation. The blastema can regenerate ectopic tails marked by red fluorescence in the host animal. Surprisingly, we also found contribution of the host animal to form the regenerate. Conclusion: We have established a useful new tool to label grafts in Xenopus transplantation experiments. http://www.biomedcentral.com/1471-213X/9/37 Christoph Waldner Magdalena Roose Gerhart Ryffel BMC Developmental Biology 2009, 9:37 2009-06-23T00:00:00Z doi:10.1186/1471-213X-9-37 BMC Developmental Biology 1471-213X 9 37 2009-06-23T00:00:00Z XML Background: Partial loss of function of the transcription factor FOXL2 leads to premature ovarian failure in women. In animal models, Foxl2 is required for maintenance, and possibly induction, of female sex determination independently of other critical genes, e.g., Rspo1. Here we report expression profiling of mouse ovaries that lack Foxl2 alone or in combination with Wnt4 or Kit/c-Kit. Results: Following Foxl2 loss, early testis genes (including Inhbb, Dhh, and Sox9) and several novel ovarian genes were consistently dysregulated during embryonic development. In the absence of Foxl2, expression changes affecting a large fraction of pathways were opposite those observed in Wnt4-null ovaries, reinforcing the notion that these genes have complementary actions in ovary development. Loss of one copy of Foxl2 revealed strong gene dosage sensitivity, with molecular anomalies that were milder but resembled ovaries lacking both Foxl2 alleles. Furthermore, a Foxl2 transgene disrupted embryonic testis differentiation and increased the levels of key female markers. Conclusions: The results, including a comprehensive principal component analysis, 1) support the proposal of dose-dependent Foxl2 function and anti-testis action throughout ovary differentiation; and 2) identify candidate genes for roles in sex determination independent of FOXL2 (e.g., the transcription factors IRX3 and ZBTB7C) and in the generation of the ovarian reserve downstream of FOXL2 (e.g., the cadherin-domain protein CLSTN2 and the sphingomyelin synthase SGMS2). The gene inventory is a first step toward the identification of the full range of pathways with partly autonomous roles in ovary development, and thus provides a framework to analyze the genetic bases of female fertility. http://www.biomedcentral.com/1471-213X/9/36 Jose Elias Garcia-Ortiz Emanuele Pelosi Shakib Omari Timur Nedorezov Yulan Piao Jesse Karmazin Manuela Uda Antonio Cao Steve Cole Antonino Forabosco David Schlessinger Chris Ottolenghi BMC Developmental Biology 2009, 9:36 2009-06-18T00:00:00Z doi:10.1186/1471-213X-9-36 BMC Developmental Biology 1471-213X 9 36 2009-06-18T00:00:00Z PDF Background In the hermaphrodite of the nematode Caenorhabditis elegans, the first germ cells differentiate as sperm. Later the germ line switches to the production of oocytes. This process requires the activity of a genetic regulatory network that includes among others the fem, fog and mog genes. The function of some of these genes is germline specific while others also act in somatic tissues. DEAD box proteins have been shown to be involved in the control of gene expression at different steps such as transcription and pre-mRNA processing.Results We show that the Caenorhabditis elegans gene mel-46 (maternal effect lethal) encodes a DEAD box protein that is related to the mammalian DDX20/Gemin3/DP103 genes. mel-46 is expressed throughout development and mutations in mel-46 display defects at multiple developmental stages. Here we focus on the role of mel-46 in the hermaphrodite germ line. mel-46(yt5) mutant hermaphrodites are partially penetrant sterile and fully penetrant maternal effect lethal. The germ line of mutants shows variable defects in oogenesis. Further, mel-46(yt5) suppresses the complete feminization caused by mutations in fog-2 and fem-3, two genes that are at the top and the center, respectively, of the genetic germline sex determining cascade, but not fog-1 that is at the bottom of this cascade.Conclusions The C. elegans gene mel-46 encodes a DEAD box protein that is required maternally for early embryogenesis and zygotically for postembryonic development. In the germ line, it is required for proper oogenesis. Although it interacts genetically with genes of the germline sex determination machinery its primary function appears to be in oocyte differentiation rather than sex determination. Ryuji Minasaki Alessandro Puoti Adrian Streit BMC Developmental Biology 2009, 9:35 2009-06-17T00:00:00Z doi:10.1186/1471-213X-9-35 BMC Developmental Biology 1471-213X 9 35 2009-06-17T00:00:00Z PDF Background: Pancreatic islets are not fully developed at birth and it is not clear how are they vascularised and innervated. Nerve Growth Factor (NGF) is required to guide sympathetic neurons that innervate peripheral organs and also in cardiovascular system and ovary angiogenesis. A transgenic mouse over-expressing NGF in pancreatic beta cells attracts sympathetic hyper-innervation to them. Moreover, we have previously demonstrated that adult beta cells synthesize and secrete NGF; however, we do not know how is NGF secreted during development, nor if it might be trophic for sympathetic innervation and survival in the pancreas.We analyzed sympathetic innervation and vasculature development in rat pancreatic islets at different developmental stages; foetal (F19), early postnatal (P1), weaning period (P20) and adults. We temporarily correlated these events to NGF secretion by islet cells. Results: Sympathetic fibres reached pancreatic islets in the early postnatal period, apparently following blood vessels. The maximal number of sympathetic fibres (TH immunopositive) in the periphery of the islets was observed around day 20, and then fibres entered and reached the core where beta cells are mainly located. The number of fibres decreased from that stage to adulthood. At all studied stages, islet cells secreted NGF and also expressed the high affinity receptor TrkA. Foetal and neonatal isolated islet cells secreted more NGF than adults. TrkA receptors were expressed at all stages in pancreatic sympathetic fibres and blood vessels. The last structures were NGF- immunoreactive only at early stages (foetal and P0). Conclusions: The results suggest that NGF signalling play an important role in the guidance of blood vessels and sympathetic fibres toward the islets during foetal and neonatal stages and could also preserve innervation at later stages of life. http://www.biomedcentral.com/1471-213X/9/34 Siraam Cabrera-Vasquez Victor Navarro-Tableros Carmen Sanchez-Soto Gabriel Gutierrez-Ospina Marcia Hiriart BMC Developmental Biology 2009, 9:34 2009-06-17T00:00:00Z doi:10.1186/1471-213X-9-34 BMC Developmental Biology 1471-213X 9 34 2009-06-17T00:00:00Z PDF Background: Biological processes are regulated by complex interactions between transcription factors and signalling molecules, collectively described as Genetic Regulatory Networks (GRNs). The characterisation of these networks to reveal regulatory mechanisms is a long-term goal of many laboratories. However compiling, visualising and interacting with such networks is non-trivial. Current tools and databases typically focus on GRNs within simple, single celled organisms. However, data is available within the literature describing regulatory interactions in multi-cellular organisms, although not in any systematic form. This is particularly true within the field of developmental biology, where regulatory interactions should also be tagged with information about the time and anatomical location of development in which they occur.DescriptionWe have developed myGRN (http://www.myGRN.org), a web application for storing and interrogating interaction data, with an emphasis on developmental processes. Users can submit interaction and gene expression data, either curated from published sources or derived from their own unpublished data. All interactions associated with publications are publicly visible, and unpublished interactions can only be shared between collaborating labs prior to publication. Users can group interactions into discrete networks based on specific biological processes. Various filters allow dynamic production of network diagrams based on a range of information including tissue location, developmental stage or basic topology. Individual networks can be viewed using myGRV, a tool focused on displaying developmental networks, or exported in a range of formats compatible with third party tools. Networks can also be analysed for the presence of common network motifs. We demonstrate the capabilities of myGRN using a network of zebrafish interactions integrated with expression data from the zebrafish database, ZFIN. Conclusion: Here we are launching myGRN as a community-based repository for interaction networks, with a specific focus on developmental networks. We plan to extend its functionality, as well as use it to study networks involved in embryonic development in the future. http://www.biomedcentral.com/1471-213X/9/33 Jamil Bacha James Brodie Matthew Loose BMC Developmental Biology 2009, 9:33 2009-06-06T00:00:00Z doi:10.1186/1471-213X-9-33 BMC Developmental Biology 1471-213X 9 33 2009-06-06T00:00:00Z XML Background: Ectodysplasin-A appears to be a critical component of branching morphogenesis. Mutations in mouse Eda or human EDA are associated with absent or hypoplastic sweat glands, sebaceous glands, lacrimal glands, salivary glands (SMGs), mammary glands and/or nipples, and mucous glands of the bronchial, esophageal and colonic mucosa. In this study, we utilized EdaTa (Tabby) mutant mice to investigate how a marked reduction in functional Eda propagates with time through a defined genetic subcircuit and to test the proposition that canonical NFκB signaling is sufficient to account for the differential expression of developmentally regulated genes in the context of Eda polymorphism. Results: The quantitative systems analyses do not support the stated hypothesis. For most NFκB-regulated genes, the observed time course of gene expression is nearly unchanged in Tabby (EdaTa) as compared to wildtype mice, as is NFκB itself. Importantly, a subset of genes is dramatically differentially expressed in Tabby (Edar, Fgf8, Shh, Egf, Tgfa, Egfr), strongly suggesting the existence of an alternative Eda-mediated transcriptional pathway pivotal for SMG ontogeny. Experimental and in silico investigations have identified C/EBPα as a promising candidate. Conclusion: In Tabby SMGs, upregulation of the Egf/Tgfα/Egfr pathway appears to mitigate the potentially severe abnormal phenotype predicted by the downregulation of Fgf8 and Shh. Others have suggested that the buffering of the phenotypic outcome that is coincident with variant Eda signaling could be a common mechanism that permits viable and diverse phenotypes, normal and abnormal. Our results support this proposition. Further, if branching epithelia use variations of a canonical developmental program, our results are likely applicable to understanding the phenotypes of other branching organs affected by Eda (EDA) mutation. http://www.biomedcentral.com/1471-213X/9/32 Michael Melnick Robert Phair Smadar Lapidot Tina Jaskoll BMC Developmental Biology 2009, 9:32 2009-06-06T00:00:00Z doi:10.1186/1471-213X-9-32 BMC Developmental Biology 1471-213X 9 32 2009-06-06T00:00:00Z XML Background: In vertebrates, the inner ear is comprised of the cochlea and vestibular system, which develop from the otic vesicle. This process is regulated via inductive interactions from surrounding tissues. Tbx1, the gene responsible for velo-cardio-facial syndrome/DiGeorge syndrome in humans, is required for ear development in mice. Tbx1 is expressed in the otic epithelium and adjacent periotic mesenchyme (POM), and both of these domains are required for inner ear formation. To study the function of Tbx1 in the POM, we have conditionally inactivated Tbx1 in the mesoderm while keeping expression in the otic vesicle intact. Results: Conditional mutants (TCre-KO) displayed malformed inner ears, including a hypoplastic otic vesicle and a severely shortened cochlear duct, indicating that Tbx1 expression in the POM is necessary for proper inner ear formation. Expression of the mesenchyme marker Brn4 was also lost in the TCre-KO. Brn4-;Tbx1+/-embryos displayed defects in growth of the distal cochlea. To identify a potential signal from the POM to the otic epithelium, expression of retinoic acid (RA) catabolizing genes was examined in both mutants. Cyp26a1 expression was altered in the TCre-KO, while Cyp26c1 showed reduced expression in both TCre-KO and Brn4-;Tbx1+/- embryos. Conclusion: These results indicate that Tbx1 expression in the POM regulates cochlear outgrowth potentially via control of local retinoic acid activity. http://www.biomedcentral.com/1471-213X/9/31 Evan Braunstein Dennis Monks Vimla Aggarwal Jelena Arnold Bernice Morrow BMC Developmental Biology 2009, 9:31 2009-05-29T00:00:00Z doi:10.1186/1471-213X-9-31 BMC Developmental Biology 1471-213X 9 31 2009-05-29T00:00:00Z XML