Enhanced cytoplasmic sequestration of the nuclear export receptor CRM1 by NS2 mutations developed in the host regulates parvovirus fitness

To investigate whether a DNA virus can evade passive immunotherapy with a polyclonal antiserum, we analyzed the protection of a neutralizing capsid antiserum against a lethal infection of the immunosuppressive strain of the parvovirus minute virus of mice (MVMi) in 42 immunodeficient mice over a period of 200 days. A few mice were effectively protected, but most developed a delayed lethal leukopenic syndrome during the treatment or weeks afterwards. Unexpectedly, viruses isolated from treated but also from control leukopenic mice showed no amino acid changes throughout the entire capsid coding region, although the viral populations were genetically heterogeneous, mainly in the second exon of the coding sequence of the NS2 nonstructural protein. The NS2 point amino acid changes (T88A, K96E, L103P, and L153 M) that were consistently selected in several mice clustered within the nuclear exportin CRM1 binding domain, in a reading frame that did not alter the overlapping NS1 coding region. These mutations endowed emerging viruses with an increased fitness that was demonstrable by their relative resistance to the neutralizing capsid antiserum in a postentry plaque-forming assay, the rapid overgrowth of a competing wild-type (wt) population in culture, and a larger yield of infectious particles. Mutant NS2 proteins interacted with a higher affinity and sequestered CRM1 in the perinuclear region of the cytoplasm more efficiently than the wt. Correspondingly this phenomenon, as well as the following timely ordered release of the NS1 nonstructural protein and the empty capsid from the nucleus to the cytoplasm, occurred markedly earlier in the infection cycle of the mutant viruses. We hypothesize that the enhanced cytoplasmic sequestration of CRM1 by the NS2 mutations selected in mice may trigger pleiotropic effects leading to an accelerated MVMi life cycle and thus to increased fitness. These results strengthen our earlier report on the rapid evolutionary capacity of this mammalian-specific DNA virus in vivo and indicate that the NS2-CRM1 interaction is an important determinant of parvovirus virulence that can be modulated in nature, hampering the effectiveness of passive antibody therapies in the long term.     

Sulfate-reducing bacteria Desulfobulbus sp. strain BH from a freshwater lake in Guizhou Province, China

Sulfate-reducing bacteria (SRB) from the anaerobic sediments of the freshwater Baihua Lake (Guizhou Province, China) at eutrophicated sites polluted with heavy metals, particularly with mercury, have been studied. SRB belonging to the genus Desulfobulbus prevailed. A detailed study of the dominating Desulfobulbus isolate designated as strain BH revealed its difference in regards to genetic, morphological, physiological, and biochemical characteristics from the other species of this genus. Strain BH utilized a wide range of organic substrates, demonstrated a high level of hydrogen sulfide production, and could be considered an important component of the microbial community in the polluted lake.     

What is the phylogenetic placement of Dipteronia dyerana Henry? An example of plant species placement based on nucleotide sequences

Abstract

DNA sequence data have been widely used to evaluate species delimitations and examine infraspecific relationships. However, species placements inferred from different nucleotide sequences are frequently in conflict. As an example of plant species placement based on nucleotide sequences, the phylogenetic placement of Dipteronia dyerana Henry (Aceraceae) was analyzed in the present study. The study species included eight Acer species (from different sections of Acer), two Dipteronia species, and two outgroup taxa. Phylogenetic trees based on five datasets (ITS, trnL‐F, trnD‐trnT, psbM‐trnD, and rpl16 regions) as well as their combined datasets were generated by using maximum parsimony (MP) and maximum likelihood (ML) analyses. Further analyses were conducted to compare the strict consensus trees based on single regions and the combination of different regions. The results revealed a significant discrepancy among the phylogenetic placements of D. dyerana, inferred from various sequences. Phylogenetic trees using MP analysis based on trnD‐trnT, rpl16, and the four chloroplast combined sequences supported the genus Dipteronia as a monophyletic group, while in the other trees D. dyerana was positioned either in parallel with D. sinensis and Acer species or within the genus Acer. In ML analysis, only rpl16 and the four chloroplast combined sequence datasets supported the genus Dipteronia as a monophyletic group. We concluded that, although significant genetic differentiation occurred between D. dyerana and D. sinensis, D. dyerana was more advanced than D. sinensis. However, whether Dipteronia is monophyletic remains to be further investigated, e.g., by using more closely related taxa and more sequences. Furthermore, in addition to internal transcribed spacer sequences, more chloroplast gene sequences should be used for phylogenetic analyses of species.     

Endogenously Expressed Truncated P2X7 Receptor Lacking the C-Terminus is Preferentially Upregulated in Epithelial Cancer Cells and Fails to Mediate Ligand-Induced Pore Formation and Apoptosis

A truncated naturally occurring variant of the human purinergic receptor P2X7 (P2X7-R) was found in human cancer cervical cells. The novel protein consists of 258 amino acids, and compared to the wild-type P2X7-R it lacks the entire intracellular carboxy terminus, the second transmembrane domain, and the distal third of the extracellular loop. The truncated P2X7-R failed to form pores and mediate apoptosis, and it interacted with the wild-type P2X7-R in a manner suggesting auto-hetero-oligomerization. In contrast to cancer cells the novel truncated P2X7-R was expressed relatively little in normal cervical cells. These data raise the possibility that coexpression of the truncated form could block P2X7 mediated apoptosis and promote uncontrolled growth of cells.     

Prolonging bovine sperm-oocyte incubation in modified medium 199 improves embryo development rate and the viability of vitrified blastocysts

This study was conducted to compare the efficacy of four in vitro fertilization (IVF) media: Bracket and Oliphant's medium (BO), modified medium 199 (IVF-M199), modified Tyrode's medium (MTM), and modified KSOM (m-KSOM) on fertilization efficiency and blastocyst formation rate. In addition, we wanted to investigate the benefit of prolonging the IVF period (from 6 to 18 h) using the two most effective IVF media determined in our initial experiment; subsequently, blastocyst viability was assessed following vitrification. A higher incidence of polyspermic fertilization was observed in the MTM (6%) and in BO, in both the 6 and 18 h (7% and 11%, respectively) groups, than in the m-KSOM (1%) or in the IVF-M199 6 or 18 h (1 and 3%, respectively) groups. Cleavage rates were similar in BO, IVF-M199, and MTM 48 h post-fertilization; however, the lowest cleavage rate was observed for m-KSOM. A greater proportion of zygotes developed into 8-cell embryos in IVF-M199 than in other IVF media. Subsequently, a greater proportion of blastocyst formation and hatching was achieved in IVF-M199 (40% and 79%, respectively) or BO (35% and 74%, respectively) than in m-KSOM (18% and 58%, respectively) or MTM (22% and 66%, respectively). Prolonging IVF to 18 h did not alter cleavage rates; however, the highest rate of overall blastocyst formation was achieved in the IVF-M199 18 h (49%), rather than in the BO 18 h (20%) group. Vitrified/thawed blastocysts from IVF-M199 groups re-expanded and developed better, as compared to the BO 18 h group, and hatching rate and total cell number in IVF-M199 18 h group was comparable to the control groups (non-vitrified). Vitrification reduced survival compared to controls. In conclusion, IVF-M199 was successfully used for IVF, compared favorably to BO medium, and offered the advantage of an extended IVF period for up to 18 h that requires only one-half a dose of semen, and resulted in better quality blastocysts that endured vitrification with a hatching rate comparable to that of control groups.     

Phytoestrogen α-zearalanol antagonizes homocysteine-induced imbalance of nitric oxide/endothelin-1 and apoptosis in human umbilical vein endothelial cells

Although the issue of estrogen replacement therapy on cardiovascular health is debatable, it has presumable benefits for endothelial function in postmenopausal women. However, the fear of breast cancer has intimidated women contemplating estrogen treatment and limited its long-term application. An effective alternative remedy not associated with breast carcinoma is in serious demand. This study was designed to examine the effect of phytoestrogen alpha-zearalanol (alpha-ZAL) and 17beta-estradiol (E2) on nitric oxide (NO) and endothelin (ET)-1 levels, apoptosis, and apoptotic enzymes in human umbilical vein endothelial cells (HUVEC). HUVEC cells were challenged for 24 h with homocysteine (10-3 M), an independent risk factor for a variety of vascular diseases, in the presence of alpha-ZAL or E2 (10-9 to 10-6 M). Release of NO and ET-1 were measured with enzyme immunoassay. Apoptosis was evaluated by fluorescence-activated cell sorter analysis. Expression of endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), Bax, and Bcl-2 were determined using Western blot. NOS activity was evaluated with 3H-arginine to 3H-citrulline conversion. Our results indicated that Hcy significantly reduced NO production, NOS activity, enhanced ET-1/NO ratio and apoptosis, upregulated iNOS, Bax, and downregulated eNOS, Bcl-2 expression. These effects were significantly attenuated by alpha-ZAL and E2. ZAL displayed a similar potency compared with E2 in antagonizing Hcy-induced effects. In summary, these results suggested that alpha-ZAL may effectively preserve Hcy-induced decrease in NO, increase in ET-1/NO ratio and apoptosis, which contributes to protective effects of phytoestrogens on endothelial function.     

Leaf water content and palisade cell size

The palisade cell sizes in leaves of Eucalyptus pauciflora were estimated in paradermal sections of cryo-fixed leaves imaged in the cryo-scanning electron microscope, as a quantity called the cell area fraction (CAF). Cell sizes were measured in detached leaves as a function of leaf water content, in intact leaves in the field during a day"s transpiration as a function of balance pressure of adjacent leaves, and on leaf disks equilibrated with air of relative humidities from 100 to 58%. Values of CAF ranged from 0.82 at saturation to approx. 0.3 in leaves dried to a relative water content (RWC) of 0.5, and in the field to approx. 0.58 at 15 bar (1.5 MPa) balance pressure. At a CAF of 0.58, the moisture content of the cell walls is in equilibrium with air at 90% relative humidity, which is the estimated relative humidity in the intercellular spaces. It is shown that at this moisture content, the cell walls could be exerting a pressure of approx. 50 bar on the cell contents.     

Effects of delayed mating and male mating history on longevity and reproductive performance of the rice stem borer, Chilo suppressalis (Walker) (Lep., Pyralidae)

Abstract:  The mating potential, effects of delayed mating and male mating history on longevity and reproductive performance of female rice stem borer (RSB), Chilo suppressalis , were investigated under laboratory conditions. Given the opportunity, RSB males copulated an average of 2.7 times, while females generally mated only once. Females were more severely affected by mating delay than males in terms of female longevity and reproductive performance. With increasing age at mating, females' longevity increased, while oviposition period, fecundity and egg fertility decreased. Mean fecundity and egg fertility of females mated 1 and 7 days after emergence were 251.3% and 99.2%, and 96.2% and 75.5% respectively. Both were reduced significantly when female mating was delayed beyond 4 days after emergence. However, irrespective of the first mating age and different mating history of the males, the results indicated that both did not result in a significant difference in the quality of their contributions to female longevity and reproductive performance. The results obtained in this study are discussed in relation to the potential effect on pheromone control of RSB.