Shi Y, Zhao S, Li J, Mao B
Biochem Biophys Res Commun. 2009 Oct 23;388(3):506-10
Islet-1 is a LIM domain transcription factor involved in several processes of embryonic development. Xenopus Islet-1 (Xisl-1) has been shown to be crucial for proper heart development. Here we show that Xisl-1 and Xisl-2 are differentially expressed in the nervous system in Xenopus embryos. Knock-down of Xisl-1 by specific morpholino leads to severe developmental defects, including eye and heart failure. Staining with the neuronal markers N-tubulin and Xisl-1 itself reveals that the motor neurons and a group of ventral interneurons are lost in the Xisl-1 morphants. Terminal dUTP nick-end labeling (TUNEL) analysis shows that Xisl-1 morpholino injection induces extensive apoptosis in the ventral neural plate, which can be largely inhibited by the apoptosis inhibitor M50054. We also find that over-expression of Xisl-1 is able to promote cell proliferation and induce Xstat3 expression in the injected side, suggesting a potential role for Xisl-1 in the regulation of cell proliferation in co-operation with the Jak-Stat pathway.
Xia Y-J, Zhao S-H, Mao B-Y
Zool Res. 2012 Dec;33(E5-6):E82–8
Xenopus ZFP36L1 (zinc finger protein 36, C3H type-like 1) belongs to the ZFP36 family of RNA-binding proteins, which contains two characteristic tandem CCCH-type zinc-finger domains. The ZFP36 proteins can bind AU-rich elements in 3' untranslated regions of target mRNAs and promote their turnover. However, the expression and role of ZFP36 genes during neural development in Xenopus embryos remains largely unknown. The present study showed that Xenopus ZFP36L1 was expressed at the dorsal part of the forebrain, forebrain-midbrain boundary, and midbrain-hindbrain boundary from late neurula stages to tadpole stages of embryonic development. Overexpression of XZFP36L1 in Xenopus embryos inhibited neuralinduction and differentiation, leading to severe neural tube defects. The function of XZP36L1 requires both its zinc finger and C terminal domains, which also affect its subcellular localization. These results suggest that XZFP36L1 is likely involved in neural development in Xenopus and might play an important role in post-transcriptional regulation.
Zanardelli S, Christodoulou N, Skourides PA
Dev Biol. 2013 Dec 1;384(1):83-100
Calpains are a family of calcium-dependent intracellular cysteine proteases that regulate several physiological processes by limited cleavage of different substrates. The role of Calpain2 in embryogenesis is not clear with conflicting evidence from a number of mouse knockouts. Here we report the temporal and spatial expression of Calpain2 in Xenopus laevis embryos and address its role in Xenopus development. We show that Calpain2 is expressed maternally with elevated expression in neural tissues and that Calpain2 activity is spatially and temporally regulated. Using a Calpain inhibitor, a dominant negative and a morpholino oligonoucleotide we demonstrate that impaired Calpain2 activity results in defective convergent extension both in mesodermal and neural tissues. Specifically, Calpain2 downregulation results in loss of tissue polarity and blockage of mediolateral intercalation in Keller explants without affecting adherens junction turnover. We further show that Calpain2 is activated in response to Wnt5a and that the inhibitory effect of Wnt5a expression on animal cap elongation can be rescued by blocking Calpain2 function. This suggests that Calpain2 activity needs to be tightly regulated during convergent extension. Finally we show that expression of Xdd1 blocks the membrane translocation of Calpain2 suggesting that Calpain2 activation is downstream of Dishevelled. Overall our data show that Calpain2 activation through the Wnt/Ca(2+) pathway and Dishevelled can modulate convergent extension movements.
Ioannou A, Santama N, Skourides PA
Dev Biol. 2013 Aug;380(2):243–58
Nucleotide binding protein 1 (Nubp1) is a highly conserved phosphate loop (P-loop) ATPase involved in diverse processes including iron-sulfur proteinassembly, centrosome duplication and lung development. Here, we report the cloning, expression and functional characterization of Xenopus laevisNubp1. We show that xNubp1 is expressed maternally, displays elevated expression in neural tissues and is required for convergent extensionmovements and neural tube closure. In addition, xNubp1knockdown leads to defective ciliogenesis of the multi-ciliated cells of the epidermis as well as the monociliated cells of the gastrocoel roof plate. Specifically, xNubp1 is required for basal body migration, spacing and docking in multi-ciliated cells and basal body positioning and axoneme elongation in monociliated gastrocoel roof plate cells. Live imaging of the different pools of actin and basal body migration during the process of ciliated cell intercalation revealed that two independent pools of actin are present from the onset of cell intercalation; an internal network surrounding the basal bodies, anchoring them to the cell cortex and an apical pool of punctate actin which eventually matures into the characteristic apical actin network. We show that xNubp1 colocalizes with the apical actin network of multiciliated cells and that problems in basal body transport in xNubp1 morphants are associated with defects of the internal network of actin, while spacing and polarity issues are due to a failure of the apical and sub-apical actin pools to mature into a network. Effects of xNubp1 knockdown on the actincytoskeleton are independent of RhoA localization and activation, suggesting that xNubp1 may have a direct role in the regulation of the actincytoskeleton.
Corkett CJ
Crustaceana. 1967;12(3):261-273
Ce travail décrit la forme du corps et la segmentation de tous les stades copépodites de Temora longicornis (O. F. Müller). L'auteur s'efforce de faire ressortir les caractères les plus propres à marquer la différence entre les divers stades et à en préciser le sexe. Un tableau indique le nombre des segments thoraciques distincts, des segments de l'abdomen, et des paires de pattes à chaque stade. Il est possible d'identifier celui-ci par le nombre et la disposition des poils sur l'endopode du maxillipède. Tous les appendices des stades copépodites sont décrits en détail et les pièces buccales figurées; le texte montre les différences principales entre les appendices des stades copépodites II à V et de l'adulte, et les appendices du stade copépodite I. La disposition des poils sur tous les appendices à tous les stades copépodites est exposée sous forme de tableau., Ce travail décrit la forme du corps et la segmentation de tous les stades copépodites de Temora longicornis (O. F. Müller). L'auteur s'efforce de faire ressortir les caractères les plus propres à marquer la différence entre les divers stades et à en préciser le sexe. Un tableau indique le nombre des segments thoraciques distincts, des segments de l'abdomen, et des paires de pattes à chaque stade. Il est possible d'identifier celui-ci par le nombre et la disposition des poils sur l'endopode du maxillipède. Tous les appendices des stades copépodites sont décrits en détail et les pièces buccales figurées; le texte montre les différences principales entre les appendices des stades copépodites II à V et de l'adulte, et les appendices du stade copépodite I. La disposition des poils sur tous les appendices à tous les stades copépodites est exposée sous forme de tableau.
Bowen WR, Lovitt RW, Wright CJ
J Colloid Interface Sci. 2000 Aug 15;228(2):428-433
An atomic force microscope has been used to quantify directly the adhesion between single Aspergillus niger spores and freshly cleaved mica surfaces. The measurements used "spore probes" constructed by immobilizing a single spore at the apex of a tipless AFM cantilever. Adhesion was quantified from force-distance data for the retraction of the spore from the surface. Studies in NaCl solutions over a range of pH and electrolyte concentration showed that the decrease of long-range electrostatic repulsion with decreasing pH provided a contribution in increasing the overall adhesion, but the variation of such repulsion with ionic strength did not correlate with changes in the magnitude of adhesion. Specific interactions between appendages and protusions on the spore surface must play an important role in adhesion. The AFM spore probe technique provides a useful new method for evaluating the interactions of spores and surfaces. It has the potential to become a powerful asset for both fundamental studies and the assessment of new materials with low adhesion properties.
Clandinin TR, Zipursky S
Neuron. 2000 Nov;28(2):427–36
In the Drosophila compound eye, photoreceptors (R cells) that respond to light from the same point in space are distributed across the retina and connect to the same target neurons. This complex connectivity pattern reconstructs visual space in the first optic ganglion, the lamina. We have used mutations that delete specific R cell subtypes or alter their retinal organization to define the cellular mechanisms that generate this pattern. R cell axons are programmed to search for targets within a local region in the lamina but their selection of appropriate postsynaptic targets requires specific interactions among R cell growth cones. The orientation of the projections is controlled both by the spatial arrangement of R cells in the retina and by cues in the target.
Nakayama K, Takebayashi Y, Namiki T, Tamahashi N, Nakayama S, Uchida T, Miyazaki K, Fukumoto M
Int J Cancer. 2001 Nov;94(4):605–9
Ovarian tumors of low malignant potential (LMP) are intermediate between adenomas and ovarian carcinomas (OC); however, the relevance of LMP to ovarian carcinogenesis is not clear. We performed a comparative analysis of allelotypes in 50 cases of LMP (42 mucinous and 8 serous) and 23 cases of OC (15 mucinous and 8 serous) to investigate any differences in genetic changes. Analysis of loss of heterozygosity (LOH) using 25 microsatellite markers reportedly associated with OC revealed that the total LOH frequency at each marker was significantly lower in LMP than in OC (p < 0.01). However, 9 (36%) loci showed higher LOH frequency in mucinous LMP than in mucinous OC. A genome-wide scan for LOH using 91 microsatellite markers and fine mapping revealed that LOH at D7S1805 (7q35) is characteristic of mucinous LMP (19.4% in mucinous LMP, 8.3% in mucinous OC). We further studied LOH in 3 cases of mucinous OC that were accompanied by mucinous LMP lesions. In 2 cases, LOH frequency was higher in the carcinoma portion than in the morphologically LMP portion. The other case showed microsatellite instability in the morphologically LMP portion and LOH in the carcinoma portion. Our results suggest the presence of an LMP-to-OC developmental sequence and the existence of a subset of LMP that does not develop into OC in the mucinous subtype of ovarian tumors.
Richard Bowen W, Stoton JAG, Doneva TA
Surf Interface Anal. 2002;33(1):7–13
Atomic force microscopy (AFM) has been used to quantify directly the interaction (adhesion) of cellubiose and cellulose with two polymeric ultrafiltration membranes of similar molecular weight cut-off (MWCO) but different materials (ES404 and EM006, PCI Membranes, UK). Membrane ES404 is made from polyethersulphone alone and EM006 is made of a polyethersulphone–polyacrylate blend chosen specifically to increase the hydrophilic properties and decrease the fouling properties of the membrane. Cellubiose-modified silica probes were used to quantify the interaction of cellubiose with the clean membranes. Pure cellulose probes were used to quantify the interaction of cellulose with both clean and cellubiose-fouled membranes. All measurements were made in 10−2m NaCl solution. It was found that the cellubiose-modified probes had three times greater adhesion with the ES404 than with the EM006 membrane. The pure cellulose probe also had greater adhesion with the ES404 membrane. Cellubiose fouling of both membranes gave close to an order of magnitude increase in the adhesion of the cellulose probe. The results show how AFM in conjunction with the colloid probe technique can elucidate surface interactions in solution, in particular how macromolecular adsorption can modify the subsequent adhesion of particulates.
Praetorius M, Baker K, Weich CM, Plinkert PK, Staecker H
ORL J Otorhinolaryngol Relat Spec. 2003 Jul;65(4):211–4
Over seventy studies have examined the potential of gene therapy in the inner ear. For the most part, they have focused on adenoviral vectors and delivery into the cochlea. Most studies have emphasized looking at the expression of marker genes driven by a CMV promoter and have used first-generation adenoviral constructs. E1/E3/E4 deleted adenoviral vectors carrying the green fluorescent protein (GFP) gene were injected into the round window, the basal turn of the cochlea (via a cochleostomy) or into the superior semicircular canal. Hearing was then tested 24 h after viral genetransfer. Large vector titers in small volumes of fluid were well tolerated with the round window approach resulting in complete hearing preservationwith transfer of GFP to hair cells and spiral ganglion cells. Injection of comparable doses of vector into a basal turn cochleostomy resulted in high-frequency hearing loss. Addition of a pancaspase inhibitor protected hearing when larger volumes of fluid were administered to the inner ear.