E-Cadherin Is Required for Centrosome and Spindle Orientation in Drosophila Male Germline Stem Cells

Many adult stem cells reside in a special microenvironment known as the niche, where they receive essential signals that specify stem cell identity. Cell-cell adhesion mediated by cadherin and integrin plays a crucial role in maintaining stem cells within the niche. In Drosophila melanogaster, male germline stem cells (GSCs) are attached to niche component cells (i.e., the hub) via adherens junctions. The GSC centrosomes and spindle are oriented toward the hub-GSC junction, where E-cadherin-based adherens junctions are highly concentrated. For this reason, adherens junctions are thought to provide a polarity cue for GSCs to enable proper orientation of centrosomes and spindles, a critical step toward asymmetric stem cell division. However, understanding the role of E-cadherin in GSC polarity has been challenging, since GSCs carrying E-cadherin mutations are not maintained in the niche. Here, we tested whether E-cadherin is required for GSC polarity by expressing a dominant-negative form of E-cadherin. We found that E-cadherin is indeed required for polarizing GSCs toward the hub cells, an effect that may be mediated by Apc2. We also demonstrated that E-cadherin is required for the GSC centrosome orientation checkpoint, which prevents mitosis when centrosomes are not correctly oriented. We propose that E-cadherin orchestrates multiple aspects of stem cell behavior, including polarization of stem cells toward the stem cell-niche interface and adhesion of stem cells to the niche supporting cells.     

Combination of Zinc and All-Trans Retinoic Acid Promotes Protection against Listeria monocytogenes Infection

Zinc (Zn) is the second most abundant transition metal after iron. It plays a vital role in living organisms and affects multiple aspects of the immune system. All-trans retinoic acid (atRA) is an isomeric form of the vitamin A or retinol. It possesses the greatest biological activity of Vitamin A. Vitamin A and related retinoids influence many aspects of immunity. In this study, we demonstrated that treatment with a combination of Zn and atRA contributes to host resistance against infection by Listeria monocytogenes. Pretreatment with Zn and atRA enhanced resistance against L. monocytogenes infection in mice and treatment with both Zn and atRA showed a higher protective effect than treatment with either alone. Supplementation with Zn, atRA or their combination decreased the number of L. monocytogenes present in target organs. In vitro, supplementation increased the bacterial uptake by macrophage cells and reduced the replication of L. monocytogenes. Our results suggest that the combination of Zn and atRA has a great bacteriostatic impact on L. monocytogenes and its infection.     

Carbon dioxide evolution of an upland rice and barley,double cropping field in central Japan

Carbon dioxide evolution rates from a double cropping, upland rice and barley field were determined in central Japan from June 1992 to May 1994, and regression models were developed to predict soil respiration rate. Diurnal patterns of hourly soil respiration rates (SRh) showed a similar trend with those of soil surface temperatures. Daily soil respiration rate (SRd) obtained by integrating SRh varied from 0.3 to 15.6 g CO₂ m⁻² for the 2 years. In the summer cropping period, SRd was positively correlated with daily mean soil surface temperature and negatively correlated with volumetric water content in soil. Moreover, this relationship was able to be expressed as a multiple-factor model with an Adj-R² of 0.925. On the other hand, in the winter cropping period, SRd was able to be represented by a single factor model using soil surface temperature with an Adj-R² of 0.854. Based on these relationships, seasonal changes in soil respiration rate were estimated. Total soil respiration rates in 1992 and 1993 estimated for the summer cropping period were 1260 g CO₂ m⁻² and 1094 g CO₂ m⁻², and for the winter cropping period 624 g CO₂ m⁻² and 676 g CO₂ m⁻², respectively. It was considered that the lower values during the summer cropping period in 1993 depended on lower soil surface temperature and higher soil water content.     

Poduction of Biotin by Microbial Transformation of dl-cis-Tetrahydro-2-oxo-4-n-pentyl-thieno-(3,4-d)-imidazoline (dl-TOPTI)

The conditions for biotin production were investigated. Urea was a more effective nitrogen source than ammonium chloride and ammonium sulfate. About 60% conversion from dl-cis-tetrahydro-2-oxo-4-n-pentyl-thieno-(3,4-d)-imidazoline (dl-TOPTI) to biotinol and biotin occurred using Corynebacterium sp. B–321. Strain M–6318 which derived from B–321 as a mutant incapable of assimilating n-alkane produced large amounts of dl-biotin from dl-TOPTI. The inability of the microbe to assimilate n-alkane resulted in repression of biotin degradation. Maximum conversion (80%) was obtained by growing cultures of strain M–6318 in the constant presence of n-paraffin.     

Nitrogen removal by co-occurring methane oxidation,denitrification, aerobic ammonium oxidation,and anammox

Quantification of microbial contaminant biodegradation based on stable isotope fractionation analysis (SIFA) relies on known, invariable isotope fractionation factors. The microbially induced isotope fractionation is caused by the preferential cleavage of bonds containing light rather than heavy isotopes. However, a number of non-isotopically sensitive steps preceding the isotopically sensitive bond cleavage may affect the reaction kinetics of a degradation process and reduce the observed (i.e., the macroscopically detectable) isotope fractionation. This introduces uncertainty to the use of isotope fractionation for the quantification of microbial degradation processes. Here, we report on the influence of bacterial cell density on observed stable isotope fractionation. Batch biodegradation experiments were performed under non-growth conditions to quantify the toluene hydrogen isotope fractionation by exposing Pseudomonas putida mt-2(pWWO) at varying cell densities to different concentrations of toluene. Observed isotope fractionation depended significantly on the cell density. When the cell density rose from 5 × 10⁵ to 5 × 10⁸cells/mL, the observed isotope fractionation declined by 70% and went along with a 55% decrease of the degradation rates of individual cells. Theoretical estimates showed that uptake-driven diffusion to individual cells depended on cell density via the overlap of the cells’ diffusion-controlled boundary layers. Our data suggest that biomass effects on SIFA have to be considered even in well-mixed systems such as the cell suspensions used in this study.     

Specific protein delivery to target cells by antibody-displaying bionanocapsules

Bionanocapsules (BNCs) are nanoparticles with a high biocompatibility composed of the L protein of the hepatitis B virus surface antigen. BNC can deliver bioactive molecules to hepatocytes efficiently and specifically. However, delivery is limited to hepatocytes and incorporation of proteins into BNC is quite troublesome. Here, in order to alter the specificity of BNC and to achieve efficient protein delivery, we developed engineered BNC displaying the ZZ domain of protein A and incorporating enhanced green fluorescent protein (EGFP) inside the particles using an insect cell expression system. The ZZ domain displayed on the surface of BNC binds to anti-epidermal growth factor receptor (EGFR) antibodies, allowing specific delivery of EGFP to HeLa cells. The engineered BNCs are a promising and powerful tool for efficient and cell-specific protein delivery.     

Molecular basis of sugar recognition by the human L-type lectins ERGIC-53, VIPL, and VIP36

ERGIC-53, VIPL, and VIP36 are related type 1 membrane proteins of the mammalian early secretory pathway. They are classified as L-type lectins because of their luminal carbohydrate recognition domain, which exhibits homology to leguminous lectins. These L-type lectins have different intracellular distributions and dynamics in the endoplasmic reticulum-Golgi system of the secretory pathway and interact with N-glycans of glycoproteins in a Ca(2+)-dependent manner, suggesting a role in glycoprotein sorting and trafficking. To understand the function of these lectins, knowledge of their carbohydrate specificity is crucial but only available for VIP36 (Kamiya, Y., Yamaguchi, Y., Takahashi, N., Arata, Y., Kasai, K. I., Ihara, Y., Matsuo, I., Ito, Y., Yamamoto, K., and Kato, K. (2005) J. Biol. Chem. 280, 37178-37182). Here we provide a comprehensive and quantitative analysis of sugar recognition of the carbohydrate recognition domains of ERGIC-53 and VIPL in comparison with VIP36 using a pyridylaminated sugar library in conjunction with frontal affinity chromatography. Frontal affinity chromatography revealed selective interaction of VIPL and VIP36 with the deglucosylated trimannose in the D1 branch of high-mannose-type oligosaccharides but with different pH dependence. ERGIC-53 bound high-mannose-type oligosaccharides with low affinity and broad specificity, not discriminating between monoglucosylated and deglucosylated high-mannosetype oligosaccharides. Based on the sugar-binding properties in conjunction with known features of these proteins, we propose a model for the action of the three lectins in glycoprotein guidance and trafficking. Moreover, structure-based mutagenesis revealed that the sugar-binding properties of these L-type lectins can be switched by single amino acid substitutions.