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Background: Genetic tools to study gene function and the fate of cells in the anterior limb bud are very limited. Results: We describe a transgenic mouse line expressing CreERT2 from the Aristaless‐like 4 (Alx4) promoter that induces recombination in the anterior limb. Cre induction at embryonic day 8.5 revealed that Alx4‐CreERT2 labeled cells using the mTmG Cre reporter contributed to anterior digits I to III as well as the radius of the forelimb. Cre activity is expanded further along the AP axis in the hindlimb than in the forelimb resulting in some Cre reporter cells contributing to digit IV. Induction at later time points labeled cells that become progressively restricted to more anterior digits and proximal structures. Comparison of Cre expression from the Alx4 promoter transgene with endogenous Alx4 expression reveals Cre expression is slightly expanded posteriorly relative to the endogenous Alx4 expression. Using Alx4‐CreERT2 to induce loss of intraflagellar transport 88 (Ift88), a gene required for ciliogenesis, hedgehog signaling, and limb patterning, did not cause overt skeletal malformations. However, the efficiency of deletion, time needed for Ift88 protein turnover, and for cilia to regress may hinder using this approach to analyze cilia in the limb. Alx4‐CreERT2 is also active in the mesonephros and nephric duct that contribute to the collecting tubules and ducts of the adult nephron. Embryonic activation of the Alx4‐CreERT2 in the Ift88 conditional line results in cyst formation in the collecting tubules/ducts. Conclusion: Overall, the Alx4‐CreERT2 line will be a new tool to assess cell fates and analyze gene function in the anterior limb, mesonephros, and nephric duct. Key Findings: Development of a new inducible Cre line that has activity on the anterior side of the limb bud and nephric tubule.Fate mapping of the anterior cells during limb bud morphogenesis. [ABSTRACT FROM AUTHOR]

We investigated the role of the chondrocyte primary cilium in mechanotransduction events related to cartilage extracellular matrix synthesis. We generated conditionally immortalized wild-type (WT) and IFT88orpk (ORPK) mutant chondrocytes that lack primary cilia and assessed intracellular Ca2+ signaling, extracellular matrix synthesis, and ATP release in response to physiologically relevant compressive strains in a 3-dimensional chondrocyte culture system. All conditions were compared to unloaded controls. We found that cilia were required for compression-induced Ca2+ signaling mediated by ATP release, and an associated up-regulation of aggrecan mRNA and sulfated glycosaminosglycan secretion. However, chondrocyte cilia were not the initial mechanoreceptors, since both WT and ORPK cells showed mechanically induced ATP release. Rather, we found that primary cilia were required for downstream ATP reception, since ORPK cells did not elicit a Ca2+ response to exogenous ATP even though WT and ORPK cells express similar levels of purine receptors. We suggest that purinergic Ca2+ signaling may be regulated by polycystin-1, since ORPK cells only expressed the C-terminal tail. This is the first study to demonstrate that primary cilia are essential organelles for cartilage mechanotransduction, as well as identifying a novel role for primary cilia not previously reported in any other cell type, namely cilia-mediated control of ATP reception. [ABSTRACT FROM AUTHOR]

We describe the localization of the golgin GMAP210 and the intraflagellar protein IFT88 in the Golgi of spermatids and the participation of these two proteins in the development of the acrosome-acroplaxome complex, the head-tail coupling apparatus (HTCA) and the spermatid tail. Immunocytochemical experiments show that GMAP210 predominates in the cis-Golgi, whereas IFT88 prevails in the trans-Golgi network. Both proteins colocalize in proacrosomal vesicles, along acrosome membranes, the HTCA and the developing tail. IFT88 persists in the acrosome-acroplaxome region of the sperm head, whereas GMAP210 is no longer seen there. Spermatids of the Ift88 mouse mutant display abnormal head shaping and are tail-less. GMAP210 is visualized in the Ift88 mutant during acrosome-acroplaxome biogenesis. However, GMAP210-stained vesicles, mitochondria and outer dense fiber material build up in the manchette region and fail to reach the abortive tail stump in the mutant. In vitro disruption of the spermatid Golgi and microtubules with Brefeldin-A and nocodazole blocks the progression of GMAP210- and IFT88-stained proacrosomal vesicles to the acrosome-acroplaxome complex but F-actin distribution in the acroplaxome is not affected. We provide the first evidence that IFT88 is present in the Golgi of spermatids, that the microtubule-associated golgin GMAP210 and IFT88 participate in acrosome, HTCA, and tail biogenesis, and that defective intramanchette transport of cargos disrupts spermatid tail development. Developmental Dynamics 240:723-736, 2011. © 2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Ift88 is a component of the intraflagellar transport complex required for formation and maintenance of cilia. Disruption of Ift88 results in depletion of cilia. The goal of the current study was to determine the role of primary cilia in ovarian function. Deletion of Ift88 in ovary using Cre-Lox recombination in mice resulted in a severe delay in mammary gland development including lack of terminal end bud structures, alterations in the estrous cycle, and impaired ovulation. Because estrogen drives the formation of end buds and Cre was expressed in the granulosa cells of the ovary, we tested the hypothesis that addition of estradiol to the mutant mice would compensate for defects in ovarian function and rescue the mammary gland phenotype. Mammary gland development including the formation of end bud structures resumed in mutant mice that were injected with estradiol. Together the results suggest that cilia are required for ovarian function. Developmental Dynamics 237:2053-2060, 2008. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Demonstrates three different developmental patterns of ovules formed on bisexual cones of Gnetum gnemon, a seed plant. Prepollination megagametophyte development; Development of megagametophyte and ovules on bisexual cones of Gnetum gnemon; Bisexuality in gnetales.