Experiments inducing prospective polar body nuclei to participate in embryogenesis of the sawfly Athalia rosae (Hymenoptera)

Summary Mature eggs dissected from ovaries of unmated females of Athalia rosae (Hymenoptera: Tenthredinidae), if placed on a filter-paper soaked with distilled water, are activated and develop to haploid males. Occasionally, however, diploid females develop from these artificially activated eggs. Treatment of mature unfertilized eggs dissected from diploid females with ice-cold temperatures immediately before activation and with a high temperature (36° C) upon and immediately after activation resulted in the production of diploid males, diploid females, triploid females and gynandromorphs at high frequency. The same treatment of mature unfertilized eggs dissected from triploid females resulted in the production of only triploid survivors. These results, together with the results on the segregation of a marker mutation, yellow fatbody (yfb), appear to indicate that meiotic divisions were complete in the treated eggs, and that all four nuclei became potentially capable of participating in development with or without automictic fusion.Studies on the sawfly, Athalia rosae (Insecta, Hymenoptera, Tenthredinidae), part V     

Galnt3 deficiency disrupts acrosome formation and leads to oligoasthenoteratozoospermia

Galnt3 belongs to the GalNAc transferase gene family involved in the initiation of mucin-type O-glycosylation. Male Galnt3-deficient (Galnt3 ^?/?) mice were infertile, as previously reported by Ichikawa et al. (2009). To investigate the involvement of Galnt3 in spermatogenesis, we examined the differentiation of germ cells in Galnt3 ^?/? mice. Galnt3 mRNA was most highly expressed in testis, and Galnt3 protein was localized in the cis-medial parts of the Golgi stacks of spermatocytes and spermatids in the seminiferous tubules. Spermatozoa in Galnt3 ^?/? mice were rare and immotile, and most of them had deformed round heads. They exhibited abnormal acrosome and disturbed mitochondria arrangement in the flagella. At the cap phase, proacrosomal vesicles of various sizes, which had not coalesced to form a single acrosomal vesicle, were attached to the nucleus in Galnt3 ^?/? mice. TUNEL-positive cells were increased in the seminiferous tubules. The binding of VVA lectin, which recognizes the Tn antigen (GalNAc-O-Ser/Thr), in the acrosomal regions of spermatids and spermatozoa in Galnt3 ^?/? mice was drastically reduced. Equatorin is a N, O-sialoglycoprotein localized in the acrosomal membrane and is suggested to be involved in sperm–egg interaction. Immunohistochemical and Western blot analyses showed a drastic reduction in the reactivity with MN9 antibody, which recognizes the O-glycosylated moiety of equatorin and inhibits sperm–egg interaction. These findings indicate that deficiency of Galnt3 results in a severe reduction of mucin-type O-glycans in spermatids and causes impaired acrosome formation, leading to oligoasthenoteratozoospermia, and suggest that Galnt3 may also be involved in the process of fertilization through the O-glycosylation of equatorin.     

Activation of the lutropin/choriogonadotropin receptor in MA-10 cells leads to the tyrosine phosphorylation of the focal adhesion kinase by a pathway that involves Src family kinases

We show that activation of the endogenous or recombinant lutropin/choriogonadotropin receptor (LHR) in mouse Leydig tumor cells (MA-10 cells) leads to the tyrosine phosphorylation of the focal adhesion kinase (FAK) and one of its substrates (paxillin). Using specific antibodies to the five tyrosine residues of FAK that become phosphorylated, we show that activation of the LHR increases the phosphorylation of Tyr576 and Tyr577, but it does not affect the phosphorylation of Tyr397, Tyr861, or Tyr925. Because FAK is a prominent substrate for the Src family of tyrosine kinases (SFKs) we tested for their involvement in the LHR-mediated phosphorylation of FAK-Tyr576. Src is not detectable in MA-10 cells, but two other prominent members of this family (Fyn and Yes) are present. The LHR-mediated phosphorylation of FAK-Tyr576 is readily inhibited by PP2 (a pharmacological inhibitor of SFKs) and by dominant-negative mutants of SKFs. Moreover, activation of the LHR in MA-10 cells results in the stimulation of the activity of Fyn and Yes, and overexpression of either of these two tyrosine kinases enhances the LHR-mediated phosphorylation of FAK-Tyr576. Studies involving activation of other G protein-coupled receptors, overexpression of the different Galpha-subunits, and the use of second messenger analogs suggest that the LHR-induced phosphorylation of FAK-Tyr576 in MA-10 cells is mediated by SFKs, and that this family of kinases is, in turn, independently or cooperatively activated by the LHR-induced stimulation of Gs and Gq/11-mediated pathways.     

Protein kinase A-regulated membrane trafficking of a green fluorescent protein-aquaporin 5 chimera in MDCK cells

The green fluorescent protein (GFP) of the jellyfish, Aeqorea victoria, was used as an autofluorescent tag to track the trafficking of aquaporin 5 (AQP5), an exocrine gland-type water channel. Two groups of chimeric proteins were constructed; one in which GFP was fused to the amino-terminus of AQP5 (GFP-AQP5) and the other, in which it was fused to the carboxyl terminus of it (AQP5-GFP). In each group, 2 chimeras were produced, a wild-type AQP5 with its normal sequence and a mutant AQP5 having a mutated amino acid at 259, i.e., GFP-AQP5-T259A and AQP5-GFP-T259A. They were used to transfect Madin-Darby canine kidney (MDCK) cells. The GFP-AQP5 chimera was localized in the intracellular vesicles, which trafficked to the plasma membrane in response to N(6), 2'-O-dibutyryladenosine 3', 5'-cyclic monophosphate (dbcAMP). Membrane trafficking was inhibited by N-[2-(p-bromocinnamylamino)ethyl]-5-isoquimolinesulfonamide (H-89) but not by palmitoyl-dl-carnitine chloride (PCC). In contrast, the AQP5-GFP chimera expressed in MDCK cells was localized constitutively on the plasma membrane. The cellular localization of the latter chimera was not affected by stimulation with dbcAMP in the presence or absence of H-89 or PCC. Replacement of Thr-259 with Ala-259 did not affect the dbcAMP-induced translocation of the chimeric protein, suggesting that phosphorylation of Thr-259 was not necessary for AQP5 trafficking under the present experimental conditions. Thus, the GFP-AQP5 chimera will be a useful tool to study AQP5 trafficking in vitro, whereas the constitutive membrane localization of the AQP5-GFP chimera suggests the importance of the carboxyl terminus of the AQP5 protein for its sorting, whether it is translocated to intracellular vesicles or to the plasma membrane.     

A CD36-related Transmembrane Protein Is Coordinated with an Intracellular Lipid-binding Protein in Selective Carotenoid Transport for Cocoon Coloration

The transport pathway of specific dietary carotenoids from the midgut lumen to the silk gland in the silkworm, Bombyx mori, is a model system for selective carotenoid transport because several genetic mutants with defects in parts of this pathway have been identified that manifest altered cocoon pigmentation. In the wild-type silkworm, which has both genes, Yellow blood (Y) and Yellow cocoon (C), lutein is transferred selectively from the hemolymph lipoprotein to the silk gland cells where it is accumulated into the cocoon. The Y gene encodes an intracellular carotenoid-binding protein (CBP) containing a lipid-binding domain known as the steroidogenic acute regulatory protein-related lipid transfer domain. Positional cloning and transgenic rescue experiments revealed that the C gene encodes Cameo2, a transmembrane protein gene belonging to the CD36 family genes, some of which, such as the mammalian SR-BI and the fruit fly ninaD, are reported as lipoprotein receptors or implicated in carotenoid transport for visual system. In C mutant larvae, Cameo2 expression was strongly repressed in the silk gland in a specific manner, resulting in colorless silk glands and white cocoons. The developmental profile of Cameo2 expression, CBP expression, and lutein pigmentation in the silk gland of the yellow cocoon strain were correlated. We hypothesize that selective delivery of lutein to specific tissue requires the combination of two components: 1) CBP as a carotenoid transporter in cytosol and 2) Cameo2 as a transmembrane receptor on the surface of the cells.     

Low-intensity pulsed ultrasound (LIPUS) induces RANKL, MCP-1, and MIP-1beta expression in osteoblasts through the angiotensin II type 1 receptor

Constant mechanical stress is essential for the maintenance of bone mass and strength, which is achieved through the cooperative functions of osteoblasts and osteoclasts. However, it has not been fully elucidated how these cell types mediate mechanical signals. Low-intensity pulsed ultrasound (LIPUS) therapy is a recently developed method for application of mechanical stress, and is used clinically to promote bone fracture healing. In the present study, we applied LIPUS to osteoblasts at different stages of maturation and analyzed their chemokine and cytokine expression. In comparison with their immature counterparts, mature osteoblasts expressed significantly higher levels of mRNAs for the receptor activator of nuclear factor kappa B ligand (RANKL), monocyte chemoattractant protein (MCP)-1, and macrophage-inflammatory protein (MIP)-1beta after a few hours of LIPUS treatment. Intriguingly, protein and mRNA expression of angiotensin II type 1 receptor (AT1), a known mechanoreceptor in cardiomyocytes, was detected in osteoblasts, and the level of expression increased significantly during cell maturation. Furthermore, LIPUS-induced extracellular signal-regulated kinase (ERK) phosphorylation and RANKL/chemokine expression was abrogated by a specific AT1 inhibitor. Thus, AT1 may play one of the essential roles in bone metabolism as a mechanoreceptor of osteoblasts.     

An ocular cysticercosis in Bali, Indonesia caused by Taenia solium Asian genotype

An ocular cysticercosis case of a nine-year-old Balinese girl in Indonesia is reported. She presented with redness and pain in the left eye and showed a cysticercus in the anterior chamber in December 2010. Morphological feature of the cysticercus removed from the anterior chamber indicated that it was an immature cysticercus of Taenia species with no hooklets. However, mitochondrial DNA analysis using a piece of histopathological specimen revealed it a cysticercus of Taenia solium Asian genotype. Serology by immunoblot and ELISA highly specific to cysticercosis was negative.