丛枝菌根真菌对中性紫色土土壤团聚体特征的影响

利用分根装置研究了接种丛枝菌根真菌对中性紫色土土壤团聚体数量、大小和稳定性的影响,分析了土壤团聚体数量、分布和分形维数,并运用通径分析对不同影响因子进行了分析。结果表明:接种G. intraradices和G. mosseae的菌根室土壤有机质和总球囊霉素相关土壤蛋白含量有增加的趋势;湿筛条件下菌根室土壤的平均重量直径(MWD)和几何平均直径(GMD)均显著高于根室土壤,而且降低了土壤分形维数,显示了丛枝菌根真菌提升土壤结构特征的作用。通径分析的结果表明,在影响MWD的众多因子中,菌丝密度对MWD有最大的直接作用。两种菌种对土壤结构均有不同程度的改良作用,反映了丛枝菌根真菌功能的多样性。     

Long-Term Trends in Visibility and at Chengdu,China

Long-term (1973 to 2010) trends in visibility at Chengdu, China were investigated using meteorological data from the U.S. National Climatic Data Center. The visual range exhibited a declining trend before 1982, a slight increase between 1983 and 1995, a sharp decrease between 1996 and 2005, and some improvements after 2006. The trends in visibility were generally consistent with the economic development and implementation of pollution controls in China. Intensive PM_2.5 measurements were conducted from 2009 to 2010 to determine the causes of visibility degradation. An analysis based on a modification of the IMPROVE approach indicated that PM_2.5 ammonium bisulfate contributed 27.7% to the light extinction coefficient (b_ext); this was followed by organic mass (21.7%), moisture (20.6%), and ammonium nitrate (16.3%). Contributions from elemental carbon (9.4%) and soil dust (4.3%) were relatively minor. Anthropogenic aerosol components (sulfate, nitrate, and elemental carbon) and moisture at the surface also were important determinants of the aerosol optical depth (AOD) at 550 nm, and the spatial distributions of both b_ext and AOD were strongly affected by regional topography. A Positive Matrix Factorization receptor model suggested that coal combustion was the largest contributor to PM_2.5 mass (42.3%) and the dry-air light-scattering coefficient (47.7%); this was followed by vehicular emissions (23.4% and 20.5%, respectively), industrial emissions (14.9% and 18.8%), biomass burning (12.8% and 11.9%), and fugitive dust (6.6% and 1.1%). Our observations provide a scientific basis for improving visibility in this area.     

Neurons important for the photoperiodic control of diapause in the bean bug, <Emphasis Type="Italic">Riptortus pedestris</Emphasis>

The morphology and functions of the brain neurons projecting to the retrocerebral complex were examined in terms of photoperiodic control of adult diapause in the bean bug, Riptortus pedestris. Backfills through the nervi corporis cardiaci stained 15-20 pairs of somata in the pars intercerebralis (PI) with contralateral axons, and 14-24 pairs in the pars lateralis (PL) with ipsilateral axons to the nervi corporis cardiaci. In the PL, two clusters of somata, PL-d and PL-v, were found. Forwardfills showed neurons in the PI terminated in the aorta, and those in the PL at the corpus cardiacum, corpus allatum, and aorta. Removal of the PI did not cause effects on diapause incidence both under short-day (12 h:12 h, light:dark) and long-day conditions (16 h:8 h, light:dark) at 25 degrees C. Under short-day conditions, diapause incidence was significantly lower than the controls after removal of the PL. Either removal of PL-d or PL-v did not reduce diapause incidence. It decreased only when both the PL-d and PL-v were ablated. The PI is not indispensable for diapause in R. pedestris, and both PL-d and PL-v neurons are suggested to be involved in photoperiodic inhibition of ovarian development.     

Enhanced Exposure of Human Immunodeficiency Virus Type 1 Primary Isolate Neutralization Epitopes through Binding of CD4 Mimetic Compounds

N-(4-Chlorophenyl)-N′-(2,2,6,6-tetramethyl-piperidin-4-yl)-oxalamide (NBD-556) is a low-molecular-weight compound that reportedly blocks the interaction between human immunodeficiency virus type 1 (HIV-1) gp120 and its receptor CD4. We investigated whether the enhancement of binding of anti-gp120 monoclonal antibodies (MAbs) toward envelope (Env) protein with NBD-556 are similar to those of soluble CD4 (sCD4) by comparing the binding profiles of the individual MAbs to Env-expressing cell surfaces. In flow cytometric analyses, the binding profiles of anti-CD4-induced epitope (CD4i) MAbs toward NBD-556-pretreated Env-expressing cell surfaces were similar to the binding profiles toward sCD4-pretreated cell surfaces. To investigate the binding position of NBD-556 on gp120, we induced HIV-1 variants that were resistant to NBD-556 and sCD4 in vitro. At passage 21 in the presence of 50 μM NBD-556, two amino acid substitutions (S375N in C3 and A433T in C4) were identified. On the other hand, in the selection with sCD4, seven mutations (E211G, P212L, V255E, N280K, S375N, G380R, and G431E) appeared during the passages. The profiles of the mutations after the selections with NBD-556 and sCD4 were very similar in their three-dimensional positions. Moreover, combinations of NBD-556 with anti-gp120 MAbs showed highly synergistic interactions against HIV-1. We further found that after enhancing the neutralizing activity by adding NBD-556, the contemporaneous virus became highly sensitive to antibodies in the patient''s plasma. These findings suggest that small compounds such as NBDs may enhance the neutralizing activities of CD4i and anti-V3 antibodies in vivo.Human immunodeficiency virus type 1 (HIV-1) replicates continuously in the face of a strong antibody (Ab) response, although Abs effectively control many viral infections (3). Neutralizing Abs (NAbs) are directed against the HIV-1 envelope (Env) protein, which is a heterodimer comprising an extensively glycosylated CD4-binding subunit (gp120) and an associated transmembrane protein (gp41). Env proteins are present on the virion surface as “spikes” composed of trimers of three gp120-gp41 complexes (20, 21, 29). These spikes resist neutralization through epitope occlusion within the oligomer, extensive glycosylation, extension of variable loops from the surface of the complex, and steric and conformational blocking of receptor binding sites (16, 18, 20).Ab access to conserved regions is further limited because viral entry is a stepwise process involving conformational changes that lead to only transient exposure of conserved domains such as the coreceptor binding site (4, 5). However, some early strains of HIV-1 appear to be highly susceptible to neutralization by Abs (1, 10). For instance, subtype A HIV-1 envelopes from the early stage of infection exhibit a broad range of neutralization sensitivities to both autologous and heterologous plasma (1), suggesting that at least a subset of the envelopes have some preserved and/or exposed neutralization epitopes. It is well known that the potential for neutralizing properties of particular Abs is enhanced after binding of soluble CD4 (sCD4), especially NAbs against CD4-induced epitopes (CD4i Abs) (27) and some anti-V3 Abs (22). CD4i Abs are detected in plasma samples from many patients at an early stage of HIV-1 infection (9). Consequently, we hypothesize that small compounds such as sCD4 can enhance the neutralizing activities of CD4i Abs and some anti-V3 Abs not only in vitro but also in vivo.In a previous report, two low-molecular-weight compounds that presumably interfere with viral entry of HIV-1 into cells were described (35). These two N-phenyl-N′-(2,2,6,6-tetramethyl-piperidin-4-yl)-oxalamide analogs, NBD-556 and NBD-557, comprise a novel class of HIV-1 entry inhibitors that block the interaction between gp120 and CD4. These compounds were found to be equally potent inhibitors of both X4 and R5 viruses in CXCR4- and CCR5-expressing cell lines, respectively (35). Schön et al. (25) also reported that NBD-556 binds to gp120 in a process characterized by a large favorable change in enthalpy that is partially compensated for by a large unfavorable entropy change, representing a thermodynamic signature similar to that observed for binding of sCD4 to gp120. In a recent study, Madani et al. (23) reported the following findings: (i) NBD-556 binds within the Phe43 cavity, a highly conserved and functionally important pocket formed as gp120 assumes the CD4-bound conformation; (ii) the NBD-556 phenyl ring projects into the Phe43 cavity; (iii) the enhancement of CD4-independent infection by NBD-556 requires the induction of conformational changes in gp120; and (iv) increased affinities of NBD-556 analogs toward gp120 improve the antiviral potency during infection of CD4-expressing cells. The latter two studies demonstrated that low-molecular-weight compounds such as NBDs can induce conformational changes in the HIV-1 gp120 glycoprotein similar to those observed upon sCD4 binding (23, 25). The authors of these studies concluded that their data supported the importance of gp120 residues near the Phe43 cavity in binding to NBD-556 and lent credence to the docked binding mode.In the present study, we investigated the binding position of NBD-556 on gp120 by inducing HIV-1 variants that were resistant to NBD-556 by exposing HIV-1_IIIB to increasing concentrations of the compound in vitro. We also induced sCD4-resistant HIV-1_IIIB variants and compared the profile of the sCD4-resistant mutations to that of the NBD-556-resistant mutations. We subsequently examined the virological properties of pseudotyped HIV-1 clones carrying the NBD-556 and sCD4 resistance-associated env gene mutations. Our findings provide a foundation for understanding the interaction of NBD-556 with the CD4-binding site of HIV-1 gp120. We also evaluated the anti-HIV-1 interactions between plasma NAbs and NBD-556 in vitro and considered the possibility of using the data as a key to opening the shield covering the conserved epitopes targeted by NAbs.(This study was presented in part at the 15th Conference on Retroviruses and Opportunistic Infection, Boston, MA, 3 to 6 February 2008 [Abstract 736].)     

Estrogen productivity of endometrium and endometrial cancer tissue; influence of aromatase on proliferation of endometrial cancer cells

Aromatase, estrone (E₁) sulfatase and E₁ sulfotransferase activities were examined in endometrium and endometrial cancer tissue preparations. Aromatase and E₁ sulfatase activities in endometrial cancer tissues were found to be significantly higher than in normal endometrial tissues. However, E₁ sulfotransferase activity did not differ between benign and malignant tissue. We also examined the effect of testosterone (T) on aromatase activity and tritiated thymidine uptake (DNA synthesis) in various cultured cervical or corpus endometrial cancer cell lines (OMC-4, HHUA, Ishikawa, HEC-59). The results demonstrated that only the HEC-59 cell line had high aromatase activity and increased its DNA synthesis in response to T. This increase of DNA synthesis by T was not suppressed by simultaneous addition of cyproterone acetate, but was by tamoxifen. These data suggest that in situ estrogen production in endometrial cancer tissue is biologically important and that aromatase in cancer cells may contribute partially to cell proliferation if androgen substrate is provided.     

Sarcocystis found in the skeletal muscle of common squirrel monkeys

Abnormally enlarged muscle fiber cells of ring form were incidentally detected in transverse sections of muscles of the common squirrel monkey during microscopic investigation of the composition of muscle fibers. Longitudinal sections showed slender capsule-like cysts in the sarcoplasm. Detailed examination revealed these cysts to be those ofSarcocystis. Among the three types of muscle fiber cells that compose the skeletal muscle, staining with Sudan black B revealed that this parasite selectively infested type II white fibers with a large diameter and a high glycogen content.     

Quasi-boundary based on exchange symmetry theory for multilevel simulations

In this contribution we propose a novel method (QUEST) which enables the simulation of diffusive systems through quantum mechanical/molecular mechanical (QM/MM) molecular dynamics. The method is an evolution of boundary based on exchange symmetry theory (BEST), an approach based on imposing a bias potential to hinder exchanges between QM and MM particles. This new method corrects for the main shortcoming of BEST, namely that only static properties could be studied, as the dynamics was disrupted. With Quasi-BEST (QUEST) the dynamics is still preserved, albeit at some additional cost in the computation of energy and forces as they are needed for the exchanged configurations between QM and MM particles. Here we describe the theoretical basis of QUEST, and we present the results on a small toy system.     

Relationship between sleep postures and sleep-disordered breathing parameters in people with Down syndrome in Japan

Sleep and Biological Rhythms - People with Down syndrome (DS) are prone to develop sleep-disordered breathing (SDB), especially obstructive sleep apnea (OSA) and they are reported to sleep in...