Niche Conservatism and Future Changes in the Potential Area Coverage of Arundina graminifolia,an Invasive Orchid Species from Southeast Asia

The Asian orchid, Arundina graminifolia, has been introduced to many locations over the last 50 yr, predominantly in South and Central America. A list of localities of A. graminifolia was compiled and used to model potential climatic niches based on the maximum entropy method. The differences are presented between niches occupied by native and invasive populations of A. graminifolia, and possible changes in the potential range of the species are discussed on the basis of various climate change scenarios. The coverage of habitats suitable for A. graminifolia will be reduced under future climate changes scenarios. The created niche distribution models indicated a more significant reduction in the potential ecological niches of the studied species in its invasive range. Nevertheless, areas with potentially suitable bioclimatic conditions for A. graminifolia should be monitored to prevent future uncontrolled invasion of the orchid into new habitats and to study its impact on the local ecosystems, as vast areas of its potential niche in the Americas are still unoccupied.     

The Na transport in gram-positive bacteria defect in the Mrp antiporter complex measured with Na nuclear magnetic resonance

²³Na nuclear magnetic resonance (NMR) has previously been used to monitor Na⁺ translocation across membranes in gram-negative bacteria and in various other organelles and liposomes using a membrane-impermeable shift reagent to resolve the signals resulting from internal and external Na⁺. In this work, the ²³Na NMR method was adapted for measurements of internal Na⁺ concentration in the gram-positive bacterium Bacillus subtilis, with the aim of assessing the Na⁺ translocation activity of the Mrp (multiple resistance and pH) antiporter complex, a member of the cation proton antiporter-3 (CPA-3) family. The sodium-sensitive growth phenotype observed in a B. subtilis strain with the gene encoding MrpA deleted could indeed be correlated to the inability of this strain to maintain a lower internal Na⁺ concentration than an external one.     

Differential expression of genes participating in cardiomyocyte electrophysiological remodeling via membrane ionic mechanisms and Ca2+-handling in human heart failure

Molecular and Cellular Biochemistry - Excitation–contraction coupling in normal cardiac function is performed with well balanced and coordinated functioning but with complex dynamic...     

Supplementation of Taurine Insulates Against Oxidative Stress,Confers Neuroprotection and Attenuates Memory Impairment in Noise Stress Exposed Male Wistar Rats

Noise has always been an important environmental factor that induces health problems in the general population. Due to ever increasing noise pollution, humans are facing multiple auditory and non-auditory problems including neuropsychiatric disorders. In modern day life it is impossible to avoid noise due to the rapid industrialization of society. Continuous exposure to noise stress creates a disturbance in brain function which may lead to memory disorder. Therefore, it is necessary to find preventive measures to reduce the deleterious effects of noise exposure. Supplementation of taurine, a semi essential amino acid, is reported to alleviate psychiatric disorders. In this study noise-exposed (100 db; 3 h daily for 15 days) rats were supplemented with taurine at a dose of 100 mg/kg for 15 days. Spatial and recognition memory was assessed using the Morris water maze and novel object recognition task, respectively. Results of this study showed a reversal of noise-induced memory impairment in rats. The derangements of catecholaminergic and serotonergic levels in the hippocampus and altered brain antioxidant enzyme activity due to noise exposure were also restored by taurine administration. This study highlights the importance of taurine supplementation to mitigate noise-induced impaired memory via normalizing the neurochemical functions and reducing oxidative stress in rat brain.

     

Identification of Avramr1 from Phytophthora infestans using long read and cDNA pathogen-enrichment sequencing (PenSeq)

Potato late blight, caused by the oomycete pathogen Phytophthora infestans, significantly hampers potato production. Recently, a new Resistance to Phytophthora infestans (Rpi) gene, Rpi-amr1, was cloned from a wild Solanum species, Solanum americanum. Identification of the corresponding recognized effector (Avirulence or Avr) genes from P. infestans is key to elucidating their naturally occurring sequence variation, which in turn informs the potential durability of the cognate late blight resistance. To identify the P. infestans effector recognized by Rpi-amr1, we screened available RXLR effector libraries and used long read and cDNA pathogen-enrichment sequencing (PenSeq) on four P. infestans isolates to explore the untested effectors. Using single-molecule real-time sequencing (SMRT) and cDNA PenSeq, we identified 47 highly expressed effectors from P. infestans, including PITG_07569, which triggers a highly specific cell death response when transiently coexpressed with Rpi-amr1 in Nicotiana benthamiana, suggesting that PITG_07569 is Avramr1. Here we demonstrate that long read and cDNA PenSeq enables the identification of full-length RXLR effector families and their expression profile. This study has revealed key insights into the evolution and polymorphism of a complex RXLR effector family that is associated with the recognition by Rpi-amr1.     

Changes in Ovaries and Uterus after Aglepristone Administration in the Third Week of Luteal Phase of Non-Pregnant Bitches

Objective

The mechanism of aglepristone action in the placentation time in the bitch remains unclear. The aim of this study was to describe the mechanism by which aglepristone influences ovaries and uterus and to measure the levels of steroid sex hormones in non-pregnant bitches.

Materials and Methods

Fourteen bitches assigned to a study (n=9) and control (n=5) group were given aglepristone and saline solution, respectively, on the 19th and 20th day after LH peak. On the 26th day after LH peak an ovariohysterectomy was performed. Blood samples were screened for estradiol and progesterone concentrations. Ovaries and uterine horns and bodies were isolated for histological and morphometrical diagnosis and immunohistochemistry analysis of α-estrogen and progesterone receptor expression.

Results

A decrease of progesterone (p<0.01) and no differences in total estrogen level in the study group were observed. There were no significant differences either in the histomorphometry or α-estrogen and progesterone receptors expression in ovaries. Increase in expression of progesterone receptors in endometrium without surface epithelium of horns (p<0.05), endometrial surface epithelium (p<0.05), myometrium of uterine body (p<0.01) and estrogen receptors in endometrium without surface epithelium of horns (p<0.05) was observed. Elevated estrogen receptors probably increased sensitivity of tissues to estrogens in the bloodstream and led to notable inflammation, haemorrhages, and hyperplasia in endometrium with mononuclear immune cell infiltration. The myometrium of horns and endometrium of uterine body of study bitches were significantly thicker than in the control group (p<0.05 and p<0.01). Furthermore myometrium of uterine body was thicker than myometrium of horns (p<0.001) and expression of progesterone receptors was higher in uterine body (p<0.01). No differences were observed between endometrium of horns and body within groups.

Conclusion

To the knowledge of the authors this is the first study, which describes the inflammatory effect developing in uterus in response to aglepristone administration, and attempts to elucidate its mechanisms.     

Liver-infiltrating lymphocytes in chronic human hepatitis C virus infection display an exhausted phenotype with high levels of PD-1 and low levels of CD127 expression

The majority of people infected with hepatitis C virus (HCV) fail to generate or maintain a T-cell response effective for viral clearance. Evidence from murine chronic viral infections shows that expression of the coinhibitory molecule PD-1 predicts CD8+ antiviral T-cell exhaustion and may contribute to inadequate pathogen control. To investigate whether human CD8+ T cells express PD-1 and demonstrate a dysfunctional phenotype during chronic HCV infection, peripheral and intrahepatic HCV-specific CD8+ T cells were examined. We found that in chronic HCV infection, peripheral HCV-specific T cells express high levels of PD-1 and that blockade of the PD-1/PD-L1 interaction led to an enhanced proliferative capacity. Importantly, intrahepatic HCV-specific T cells, in contrast to those in the periphery, express not only high levels of PD-1 but also decreased interleukin-7 receptor alpha (CD127), an exhausted phenotype that was HCV antigen specific and compartmentalized to the liver, the site of viral replication.     

Inactivation and Disassembly of the Anaphase-Promoting Complex during Human Cytomegalovirus Infection Is Associated with Degradation of the APC5 and APC4 Subunits and Does Not Require UL97-Mediated Phosphorylation of Cdh1

Infection of quiescent cells by human cytomegalovirus (HCMV) elicits severe cell cycle deregulation, resulting in a G₁/S arrest, which can be partly attributed to the inactivation of the anaphase-promoting complex (APC). As we previously reported, the premature phosphorylation of its coactivator Cdh1 and/or the dissociation of the core complex can account for the inactivation. We have expanded on these results and further delineated the key components required for disabling the APC during HCMV infection. The viral protein kinase UL97 was hypothesized to phosphorylate Cdh1, and consistent with this, phosphatase assays utilizing a virus with a UL97 deletion mutation (ΔUL97 virus) indicated that Cdh1 is hypophosphorylated at early times in the infection. Mass spectrometry analysis demonstrated that UL97 can phosphorylate Cdh1 in vitro, and the majority of the sites identified correlated with previously characterized cyclin-dependent kinase (Cdk) consensus sites. Analysis of the APC core complex during ΔUL97 virus infection showed APC dissociation occurring at the same time as during infection with wild-type virus, suggesting that the UL97-mediated phosphorylation of Cdh1 is not required for this to occur. Further investigation of the APC subunits showed a proteasome-dependent loss of the APC5 and APC4 subunits that was temporally associated with the disassembly of the APC. Immediate early viral gene expression was not sufficient for the degradation of APC4 and APC5, indicating that a viral early gene product(s), possibly in association with a de novo-synthesized cellular protein(s), is involved.Human cytomegalovirus (HCMV), a highly prevalent β-herpesvirus, can cause serious birth defects and disease in immunocompromised individuals, and it may be associated with cancer and cardiovascular disease (53). Viral gene expression is temporally regulated and is dependent on many cellular factors for a productive infection. Immediate early (IE) genes are expressed by 2 h postinfection (p.i.) and transactivate the early genes required for viral DNA replication. The expression of the late genes, which encode proteins involved in virion maturation and egress, is dependent on viral DNA replication.The virus has adopted different strategies for altering the cellular environment to make it more conducive to productive infection, including the stimulation of host cell DNA replication pathways, cell cycle deregulation and arrest, immune evasion, and inhibition of apoptosis (53). Although HCMV encodes its own DNA polymerase, it is dependent on other cellular resources for DNA replication. Infection of quiescent cells induces passage toward S phase such that the host cell is stimulated to generate proteins and DNA precursors necessary for genome replication; however, entry into S phase and cellular DNA replication are subsequently blocked and the cell arrests in G₁/S (1, 10, 11, 14, 30, 45). Cellular resources are thereby presumably free to be efficiently utilized for viral replication. Cell cycle arrest by HCMV is achieved in part through the misregulation of several cell cycle proteins, including the phosphorylation and accumulation of the Rb family pocket proteins, upregulation of cyclins E and B and their associated kinase activities, inhibition of cyclin A expression, stabilization of p53, and accumulation of Cdc6 and geminin, which inhibits licensing of the cellular origins of DNA replication (8, 17, 30, 49, 54, 65). Some of these cell cycle defects can be attributed to a deregulation of the anaphase-promoting complex (APC) (8, 72, 79, 80), an E3 ubiquitin ligase that is responsible for the timely degradation of cell cycle proteins and mitotic cyclins to promote cycle progression from mitosis through G₁ to S phase (58, 74). As the APC also appears to be a common target among other viruses, including the chicken anemia virus, adenoviruses, and poxviruses (23, 36, 52, 70), understanding the mechanisms leading to its inactivation during viral infection has been of great interest.As we have previously reported, multiple mechanisms may be involved in disabling the APC during HCMV infection (72), which is not surprising given the complexity of its structure and regulation (for a review, see references 58 and 74). The APC is a large multisubunit complex consisting of at least 11 conserved core subunits, as well as other species-specific subunits. In metazoans, the APC2 and APC11 subunits form the catalytic core, and along with APC10, provide the platform for binding the E2 ubiquitin-conjugating enzyme. Each of the APC3, APC8, APC6, and APC7 subunits contain multiple copies of the tetratricopeptide repeat (TPR) motif and together make up the TPR subcomplex, which provides a platform of protein interaction surfaces for binding the coactivators (i.e., Cdh1 and Cdc20) and various substrates. These two subcomplexes are bridged by the large scaffolding subunit APC1, with the TPR subcomplex tethered to APC1 through APC4 and APC5. The binding between APC1, APC4, APC5, and APC8 is also interdependent, such that the loss of one subunit decreases the association of the other three (71).The APC is activated by either of its coactivators, Cdh1 or Cdc20, which also function in recruiting specific substrates to the APC during different phases of the cell cycle. The phosphorylation of several APC subunits at the onset of mitosis, including APC1 and the TPR subunits, by cyclin B/cyclin-dependent kinase 1 (Cdk1) and Plk1 allows the binding of Cdc20 and subsequent activation of the APC (APC^Cdc20) (19, 37), whereas the binding and activation of the complex by Cdh1 is inhibited through its phosphorylation by cyclin B/Cdk1 (9, 29, 38, 83). As cells pass the spindle assembly checkpoint, APC^Cdc20 ubiquitinates securin (to allow for sister chromatid separation) and cyclin B for degradation by the proteasome (42, 67). The subsequent inactivation of Cdk1 and activation of mitotic phosphatases during late anaphase relieves the inhibitory phosphorylation on Cdh1, presumably by Cdc14 (6, 38, 44), which then allows Cdh1 to bind and activate the APC (APC^Cdh1). APC^Cdh1 ubiquitinates Cdc20 and mitotic cyclins for degradation to facilitate mitotic exit and maintains their low levels, along with S-phase regulators (e.g., Cdc6, geminin, etc.), during G₁ (16, 50, 59, 63). The inactivation of APC^Cdh1 as cells enter S phase may be mediated in part through the phosphorylation of Cdh1 by cyclin A/Cdk2 (46) and Cdh1 binding to the inhibitor Emi1 (25). The inactivation of Cdh1 by phosphorylation has been shown in all organisms studied thus far (e.g., yeast, Drosophila, plants, mammals, etc.), and mutants mimicking constitutively phosphorylated Cdh1 on Cdk consensus sites can neither bind nor activate the APC in vivo or in vitro (9, 29, 38, 69, 83).During HCMV infection of fibroblasts in G₀/G₁, however, Cdh1 becomes prematurely phosphorylated in a Cdk-independent manner and no longer associates with the APC (72). This dissociation does not appear to be due to an overexpression of Emi1 (79). Cdc20 also can no longer associate with the APC (79), suggesting a defect in the APC core. We have further shown that the APC core complex disassembles during the infection, with the TPR subunits (i.e., APC3, APC7, and APC8) and APC10 localizing to the cytosol, while APC1 remains nuclear (72). Interestingly, both the phosphorylation of Cdh1 and the dissociation of the APC occur at similar times during HCMV infection. Although either of these mechanisms could render the APC inactive, it was unclear whether these processes are linked or represent independent (or redundant) pathways. The causative factor(s) in mediating these events and the question of whether such a factor(s) was of cellular or viral origin also remained unresolved.On the basis of the results of several recent studies (26, 32, 62), the viral protein kinase UL97 emerged as a likely candidate for involvement in the phosphorylation of Cdh1. Conserved among herpesviruses, UL97 functions in viral genome replication (7, 32, 81) and in nuclear egress of viral capsids (21, 39, 48). UL97 is present in the tegument of the virus particle (76) and is also expressed de novo with early kinetics (i.e., detectable by 5 h p.i. by Western blot assay), with increased expression at later times of the infection (51, 76, 77). UL97 is a serine/threonine (S/T) protein kinase (22), and recent studies have further characterized it as a Cdkl mimic, with predicted structural similarity to Cdk2 (64) and common substrates. UL97 has been shown to phosphorylate in vitro nuclear lamin A/C (21), the carboxyl-terminal domain of RNA polymerase II (5), the translation elongation factor 1δ (EF1δ) (33), and Rb (26, 62) on sites targeted by Cdks, and there is considerable evidence that UL97 phosphorylates lamin A/C, EF1δ, and Rb on these sites in infected cells as well (21, 26, 33, 62). Given that cyclin A/Cdk2 and cyclin B/Cdk1 complexes normally phosphorylate Cdh1, thus preventing its association with the APC, we hypothesized that UL97 phosphorylates Cdh1 during HCMV infection.In the present study, we provide further mechanistic details of the events and players involved in inactivating the APC during HCMV infection. Evidence that UL97 is the viral factor mediating the phosphorylation of Cdh1 was obtained. However, APC disassembly still occurred at similar times in ΔUL97 and wild-type virus infections, indicating that UL97-mediated phosphorylation of Cdh1 is not required for this event. The inactivation of the APC core complex is further attributed to the loss of the APC5 and APC4 subunits early during the infection. The degradation of these subunits is proteasome dependent and requires de novo synthesis of viral early or cellular proteins. While the primary mechanism of inactivation appears to be the dissociation of the complex and the targeted loss of APC5 and APC4, phosphorylation of Cdh1 may provide a small kinetic advantage and backup mechanism for disabling the APC.