Glucose uptake stimulatory effect of akuammicine from Picralima nitida (Apocynaceae)

A bioactivity-guided fractionation of the chloroform extract of the seeds of Picralima nitida using glucose uptake in fully differentiated 3T3-L1 adipocytes afforded six indole alkaloids (akuammicine, 10-deoxyakuammine, akuammine, akuammidine, burnamine and picraline) and a mixture of four 5-hydroxy tryptamine amides. Akuammicine accounted for the increase in glucose uptake observed in the chloroform extract.     

Genetic characteristics, coreceptor usage potential and evolution of Nigerian HIV-1 subtype G and CRF02_AG isolates

HIV-1 CRF02_AG and subtype G (HIV-1G) account for most HIV infections in Nigeria, but their evolutionary trends have not been well documented. To better elucidate the dynamics of the epidemic in Nigeria we characterised the gag and env genes of North-Central Nigerian HIV-1 isolates from pregnant women. Of 28 samples sequenced in both genes, the predominant clades were CRF02_AG (39%) and HIV-1G (32%). Higher predicted proportion of CXCR4-tropic (X4) HIV-1G isolates was noted compared to CRF02_AG (p = 0.007, Fisher''s exact test). Phylogenetic and Bayesian analysis conducted on our sequences and all the dated available Nigerian sequences on the Los Alamos data base showed that CRF02_AG and HIV-1G entered into Nigeria through multiple entries, with presence of HIV-1G dating back to early 1980s. This study underlines the genetic complexity of the HIV-1 epidemic in Nigeria, possible subtype-specific differences in co-receptor usage, and the evolutionary trends of the predominant HIV-1 strains in Nigeria, which may have implications for the design of biomedical interventions and better understanding of the epidemic.     

Endophyte-induced Verticillium protection in tomato is range-restricted

Endophytes, bacterial, fungal or viral, colonize plants often without causing visible symptoms. More important, they may benefit host plants in many ways, most notably by preventing diseases caused by normally virulent pathogens. Previous studies have shown that an isolate of V. dahliae from eggplant, Dvd-E6, can colonize tomato endophytically, producing taller and more robust tomato plants while providing protection against a virulent V. dahliae, race 1 (Vd1) isolate. Expression analyses suggest this requires interplay between Dvd-E6 and the plant that involves resistance and defense genes. To examine the possibility of a broader effect, dual interactions have been further examined with a more distantly related pathogen, Verticillium albo-atrum (Vaa). The results indicate Dvd-E6 colonization selectively modifies the expression of specific tomato genes to be detrimental to Vd1 but not Vaa, providing evidence that Verticillium-induced protection is range-restricted.Key words: cross-protection, endophyte, lycopersicon, tolerance, VerticilliumAn “endophyte” commonly is defined as a “fungus or bacterium living within plants without causing visible symptoms of disease”; a “pathogen” is regarded as “a disease causing biological agent”. Historically, plant biologists have tended to consider these as two very different and distinct classes of organisms but accumulating evidence now suggests that the boundaries between mutualism and parasitism are not as defined as previously thought. Many organisms can occupy both ecological niches¹ depending on the genotype of the host, the genotype of the organism itself and interaction with the environment. Indeed, this “dual life style” may be a significant factor in the evolutionary dynamics of pathogen resistance, tolerance and susceptibility.²One of the more recent additions to the growing list of dual life style (endophyte/pathogen) fungi is Verticillium dahliae,³ a causal agent of vascular wilt disease or early dying syndrome in a broad range of the plant species.⁴ When Verticillium infects a plant three different host responses can occur: resistance, susceptibility or tolerance. The phenomenon of tolerance has been associated with Verticillium spp. for decades but research on mechanisms governing the development of the plant/Verticillium interaction has focused on the compatible and incompatible interactions and little is known about the tolerant state (reviewed in ref. ⁵). In a recent series of papers we have identified an isolate of Verticillium dahliae, known as Dvd-E6, that colonizes tomatoes, cv Craigella, resulting in a stable tolerant condition, that we have used as a model system to investigate the biological and molecular bases of plant tolerance to Verticillium spp. The Craigella/Dvd E6 interaction has a number of interesting but unanticipated properties. Host plants tend to be taller and more robust than their uninfected counterparts⁶ and colonization of Craigella by Dvd-E6 provides protection against its virulent Verticillium dahliae race 1 (Vd1) cousin, limiting both Vd1 colonization and symptom development during dual infections.⁷ Such attributes normally are associated with plant/endophyte partnerships, strongly suggesting that under some conditions, Verticillium dahliae can assume an endophytic role. Apparently interplay between Dvd-E6 and the plant establishes protection against the virulent Vd1.⁷Many endophytic infections provide protection for the host against a broad range of pathogens.¹ To test the ability of Dvd-E6 infection to protect Craigella against a more distantly related Verticillium pathogen we have now examined dual interactions with Verticillium albo-atrum (Vaa). Susceptible Craigella⁸ seedlings again were inoculated at the 4-leaf stage by dipping the roots in Vd1, Dvd-E6 or Vaa conidial suspensions (1 × 10⁷ spores/ml in 0.5% gelatin solution) to establish homogeneous interactions (reviewed in ref. ⁷). For dual interactions, seedlings were inoculated with Dvd-E6 spores at the 3-leaf stage and reinoculated at the 4-leaf stage with either Vd1 or Vaa spore suspension to establish the mixed infections. Control seedlings were root dipped in gelatin solution alone. Plants were scored for symptom expression on a 0 (no symptoms) to 5 (plant dead) scale as described by Shittu and co-workers (2009) and the top two-thirds of the stems harvested at 5 and 10 days post inoculation (d.p.i.) for extraction and fungal DNA assays.^7,9All experimental results are summarized in Figure 1. At 10 d.p.i., the disease scores for Dvd-E6-infected plants were approximately one-third that of the Vd1-or Vaa-infected plants. More interesting were the symptoms in the dual interactions, Dvd-E6/Vd1 mimicking the tolerant plants with low disease and Dvd-E6/Vaa-infected plants exhibiting the highest disease scores, similar to Vd1-or Vaa-infected plants. When the amount of fungal DNA in the stems was assessed, the total fungal biomass in both dual infections as well as the Dvd-E6 and Vd1-infected plants at 5 and 10 dpi was similar (light and dark gray bars), the amount of Vaa being somewhat lower. In the mixed infections, however, most of the DNA (>90%) was of Dvd-E6 origin (white bars). More important, the Vd1 DNA level in Dvd-E6/Vd1 plants was substantially reduced relative to plants infected with Vd1 alone while the Vaa DNA levels stayed about the same in the single and double infections. This indicates that Vd1 colonization is restricted⁷ by the presence of Dvd-E6 while Vaa is not.Open in a separate windowFigure 1Comparison of symptoms and levels of V. dahliae 1 or V. albo-atrum DNA in susceptible Craigella tomato simultaneously infected with V. dahliae Dvd-E6. Individual (E6, Vd1 and Vaa) and mixed (E6/Vd1 and E6/Vaa) infections were established as previously described.⁷ Plants were scored (upper) at 5 (light gray bars) and 10 (dark gray bars) dpi for symptoms (i.e., disease scores ± SD) or assayed⁷ for total levels of Verticillium DNA (i.e., ng/g plant tissue ± SD) in the stems (lower). In mixed infections levels for each fungus also were determined (black and white bars, respectively). Results summarize the data for 9–12 plants per time point for each interaction.These results demonstrate that Dvd-E6 infection protects Craigella tomatoes against colonization by and symptom development from Vd1 but not Vaa. Past studies often have suggested that the protective effect stems from an endophyte-induced activation of systemic acquired resistance (SAR) in the host providing protection against a broad range of pathogens.¹⁰ However, in the tolerant CS//Dvd-E6 interaction the protective effect appears to be targeted more directly, allowing Dvd-E6 to effectively restrict it''s virulent cousin, Vd1. In this context, it may be important that both of the Verticillium dahliae isolates from tomato are endemic to Ontario^7,11 and potentially in direct competition, while Verticillium albo-atrum from tomato is not. Previous molecular analyses suggested that the protective effect provided by Dvd-E6 colonization requires a genetic interplay with the host, selectively modifying the expression of specific tomato genes to be detrimental to Vd1. The experimental results presented here provide evidence that Verticillium-induced protection is restricted in range.     

Selenium status of idiopathic infertile Nigerian males

Selenium concentration in the sera and seminal plasma of 60 infertile males (40 oligospermia and 20 azoospermia) and 40 males with proven evidence of fertility (normospermia; control group) were estimated using atomic absorption spectrophotometry. Results were correlated with spermatogram and hormonal levels in order to determine their relationship and significance in male infertility. The mean serum concentrations of selenium was found to be significantly increased in oligospermic compared to azoospermic subjects and controls (p<0.01), whereas the seminal plasma level was significantly higher in azoospermic compared to oligospermic subjects and controls (p<0.001). Thus, the ratio of serum selenium to seminal plasma selenium was 1∶1 in controls, 4∶1 in oligospermia, and 1∶2 in azoospermic subject. A significant inverse correlation was observed between serum selenium level and sperm count (p<0.01). Similarly, seminal plasma selenium correlated with spermatozoa motility, viability, and morphology. Serum selenium level shows positive correlation with the serum testosterone level (p<0.01). In conclusion, there appears to be a physiological balance in the distribution of selenium in serum and seminal plasma compartment of control males. A disturbance in this balance has a significant influence on spermatogenesis. Selenium appears to have a positive influence on Leydig cells, thus influencing the secretion of testosterone.     

ABSTRACTS OF THE PROCEEDINGS OF THE 31st ANNUAL SCIENTIFIC CONFERENCE OF THE SOCIETY

Zingiber officinale (ginger) has been shown to be a rich source of antioxidants. Previous studies have shown that cryptorchidism causes oxidative stress. However, the possible effect of ginger in ameliorating cryptorchidism-induced oxidative stress in rat has not been investigated. The present study therefore looked into the effect of ethanol extract of ginger (EEG) on the oxidative stress in experimentally induced cryptorchidism in the rat. Twenty four (24) male Sprague-Dawley rats, weighing 170g-210g were divided into three (3) groups (A-C), of eight (8) rats each. Group A was sham-operated and treated with vehicle, Groups B and C were rendered cryptorchid treated with vehicle and EEG respectively. Cryptorchid rats had significantly lower testicular weight, sperm count, sperm motility, lower percentage sperms with normal morphology, superoxide dismutase (SOD),..     

Plant-endophyte interplay protects tomato against a virulent <Emphasis Type="Italic">Verticillium</Emphasis>

Endophytes, bacterial, fungal or viral, colonize plants often without causing visible symptoms. More important, they may benefit host plants in many ways, most notably by preventing diseases caused by normally virulent pathogens. Craigella tomatoes (Lycopersicon esculentum Mill.) can be infected with Verticillium dahliae Kleb., either race 1 (Vd1) or a non-host isolate Dvd-E6 resulting in susceptibility or tolerance, respectively. The present study sought to determine whether Dvd-E6 is endophytic and can protect tomato against Vd1. The total amount of Verticillium in stems and roots was determined by quantitative PCR; the relative amounts of Vd1 and Dvd-E6 were assessed by restriction fragment polymorphism. When Dvd-E6 infects before or together with Vd1, Vd1 is excluded almost completely from the root but, when Vd1 infects first, Dvd-E6 can compete on an equal basis. Previous studies suggested that Dvd-E6 suppresses symptom-related genes, raising the possibility that Dvd-E6 simultaneously induces tolerance to Vd1. This does not seem to be entirely the case since the minimal symptoms following Vd1 infection of Dvd-E6 tolerant Craigella result, at least in part, from restricted Vd1 colonization. Furthermore, when Vd1 and Dvd-E6 are cultured on PDA plates alone or together, the growth rates are similar and neither is inhibitory to the other. Dvd-E6 does not outgrow or inhibit Vd1, in vitro. The protective effect apparently requires interplay between Dvd-E6 and the plant. Expression analyses of tomato genes involved in resistance and defence support this interpretation.     

Heat-shock responsive genes identified and validated in Atlantic cod (Gadus morhua) liver, head kidney and skeletal muscle using genomic techniques

Background

The Mongolian gerbils are a good model to mimic the Helicobacter pylori -associated pathogenesis of the human stomach. In the current study the gerbil-adapted strain B8 was completely sequenced, annotated and compared to previous genomes, including the 73 supercontigs of the parental strain B128.

Results

The complete genome of H. pylori B8 was manually curated gene by gene, to assign as much function as possible. It consists of a circular chromosome of 1,673,997 bp and of a small plasmid of 6,032 bp carrying nine putative genes. The chromosome contains 1,711 coding sequences, 293 of which are strain-specific, coding mainly for hypothetical proteins, and a large plasticity zone containing a putative type-IV-secretion system and coding sequences with unknown function. The cag -pathogenicity island is rearranged such that the cag A-gene is located 13,730 bp downstream of the inverted gene cluster cag B- cag 1. Directly adjacent to the cag A-gene, there are four hypothetical genes and one variable gene with a different codon usage compared to the rest of the H. pylori B8-genome. This indicates that these coding sequences might be acquired via horizontal gene transfer. The genome comparison of strain B8 to its parental strain B128 delivers 425 unique B8-proteins. Due to the fact that strain B128 was not fully sequenced and only automatically annotated, only 12 of these proteins are definitive singletons that might have been acquired during the gerbil-adaptation process of strain B128.

Conclusion

Our sequence data and its analysis provide new insight into the high genetic diversity of H. pylori -strains. We have shown that the gerbil-adapted strain B8 has the potential to build, possibly by a high rate of mutation and recombination, a dynamic pool of genetic variants (e.g. fragmented genes and repetitive regions) required for the adaptation-processes. We hypothesize that these variants are essential for the colonization and persistence of strain B8 in the gerbil stomach during inflammation.     

Evolutionary Dynamics of Multiple Sublineages of H5N1 Influenza Viruses in Nigeria from 2006 to 2008

Highly pathogenic A/H5N1 avian influenza (HPAI H5N1) viruses have seriously affected the Nigerian poultry industry since early 2006. Previous studies have identified multiple introductions of the virus into Nigeria and several reassortment events between cocirculating lineages. To determine the spatial, evolutionary, and population dynamics of the multiple H5N1 lineages cocirculating in Nigeria, we conducted a phylogenetic analysis of whole-genome sequences from 106 HPAI H5N1 viruses isolated between 2006 and 2008 and representing all 25 Nigerian states and the Federal Capital Territory (FCT) reporting outbreaks. We identified a major new subclade in Nigeria that is phylogenetically distinguishable from all previously identified sublineages, as well as two novel reassortment events. A detailed analysis of viral phylogeography identified two major source populations for the HPAI H5N1 virus in Nigeria, one in a major commercial poultry area (southwest region) and one in northern Nigeria, where contact between wild birds and backyard poultry is frequent. These findings suggested that migratory birds from Eastern Europe or Russia may serve an important role in the introduction of HPAI H5N1 viruses into Nigeria, although virus spread through the movement of poultry and poultry products cannot be excluded. Our study provides new insight into the genesis and evolution of H5N1 influenza viruses in Nigeria and has important implications for targeting surveillance efforts to rapidly identify the spread of the virus into and within Nigeria.Since its emergence in 1996 in Guangdong, China, highly pathogenic avian influenza virus of the H5N1 subtype (HPAI H5N1 virus) has disseminated widely across Asia, Europe, and Africa, infecting a range of domestic and wild avian species and sporadically spilling over into humans and other mammals (4, 35). Over time, the HPAI H5N1 virus has diversified into multiple phylogenetically distinct lineages, classified as clades 0 to 9 according to the unified nomenclature system (33). The H5N1 lineage currently circulating in central Asia, the Middle East, Europe, and Africa is referred to as clade 2.2 (33) and has also been described as “EMA” or Qinghai-like in previous publications (4, 17, 27). This clade originated in April 2005 during a large outbreak of a phylogenetically distinct H5N1 virus among wild bird populations at Qinghai Lake in western China (4, 17) and rapidly spread west through central Asia and Europe, eventually reaching Africa in 2006 (27). Clade 2.2 has further diversified, forming the genetic third-order clade 2.2.1 (32) and three genetically distinct sublineages (I, II, and III) (2, 19, 28), all of which are found in Africa.Since 2006 HPAI H5N1 viruses belonging to clade 2.2 have disseminated across multiple countries in western, eastern, and northern Africa: Egypt, Niger, Cameroon, Sudan, Burkina Faso, Djibouti, Ivory Coast, Ghana, Togo, Benin, and Nigeria (2). With a large poultry industry, estimated at 140 million birds (11), Nigeria has experienced several major outbreaks of HPAI H5N1 virus, posing a serious threat to food security and public health in Africa. The first case of HPAI H5N1 virus in Nigeria (sublineage I) occurred in January 2006 in the state of Kaduna, and the virus subsequently was detected in Ghana, Burkina Faso, Ivory Coast, and Sudan (2). In February 2006 sublineage II was reported in Nigeria, and it disseminated widely across the country during 2006 and 2007, also appearing in Togo (2). Clade 2.2.1, which has been prevalent in Egypt, Israel, and the Gaza Strip from 2006 to 2008, was also detected in Nigeria in 2006 (10).By the end of 2007, outbreaks of HPAI H5N1 virus in Nigeria appeared to have been successfully controlled by measures such as “stamping out with compensation,” restrictions on movement of poultry, and enhanced surveillance (13). However, in July 2008 new cases of HPAI H5N1 from a sublineage never previously detected in Africa (sublineage III) were registered in the Nigerian states of Kano and Katsina and in live bird markets in Gombe and Kebbi states (13, 21). Hence, Nigeria is the only African country where viruses belonging to clade 2.2.1 and to three different sublineages (I, II, and III) of clade 2.2 have all been detected. At least three different reassortment events between sublineages have been documented in Nigeria. Salzberg et al. identified the first reassortant strain (which we refer to as “R1”), in which four genome segments (hemagglutinin [HA], NP, NS, and PB1) belong to sublineage I and the other four segments (NA, MP, PA, and PB2) are derived from sublineage II (27). Subsequently, phylogenetic analysis showed that a 2007 reassortant strain (which we refer to as “R3”) contained the HA and NS segments from sublineage I and the other six segments from sublineage II (19, 22). Another reassortant virus (which we refer to as “R5”) contained only the NS gene segment from sublineage I, while the other seven segments were derived from sublineage II (22).Although the genetic diversity of the Nigerian HPAI H5N1 virus population has been well characterized, including multiple introductions of the virus into Nigeria and several reassortment events, little is known about the evolutionary and population growth dynamics of the virus within Nigeria. Particularly understudied are the spatial movements of individual sublineages among Nigeria''s vast poultry population. To explore the spatial, evolutionary, and population dynamics of the multiple H5N1 lineages cocirculating in Nigeria, we conducted a phylogenetic analysis of whole-genome sequences from 106 HPAI H5N1 viruses isolated between 2006 and 2008 and representing all 25 Nigerian states and the Federal Capital Territory (FCT) reporting outbreaks. Using the exact date and location of collection for each viral isolate, we inferred from their phylogenetic relationships the directionality of viral gene flow among Nigerian states and identified critical regions that are likely to serve as key sources for the H5N1 virus in Nigeria.     

Specific B cell tolerance is induced by cyclosporin A plus donor-specific blood transfusion pretreatment: prolonged survival of MHC class I disparate cardiac allografts

Donor-specific blood transfusion (DST), designed to prolong allograft survival, sensitized recipients of the high-responder PVG-RT1u strain, resulting in accelerated rejection of MHC-class I mismatched (PVG-R8) allografts. Rejection was found to be mediated by anti-MHC class I (Aa) alloantibody. By pretreating recipients 4 wk before grafting with cyclosporin A (CsA) daily (x7), combined with once weekly (x4) DST, rejection was prevented. The investigation explores the mechanism for this induced unresponsiveness. CD4 T cells purified from the thoracic duct of CsA/DST-pretreated RT1u rats induced rejection when transferred to R8 heart-grafted RT1u athymic nude recipients, indicating that CD4 T cells were not tolerized by the pretreatment. To determine whether B cells were affected, nude recipients were pretreated, in the absence of T cells, with CsA/DST (or CsA/third party blood) 4 wk before grafting. The subsequent transfer of normal CD4 T cells induced acute rejection of R8 cardiac allografts in third party- but not DST-pretreated recipients; prolonged allograft survival was reversed by the cotransfer of B cells with the CD4 T cells. Graft survival correlated with reduced production of anti-MHC class I (Aa) cytotoxic alloantibody. The results indicated that the combined pretransplant treatment of CsA and DST induced tolerance in allospecific B cells independently of T cells. The resulting suppression of allospecific cytotoxic Ab correlated with the survival of MHC class I mismatched allografts. The induction of B cell tolerance by CsA has important implications for clinical transplantation.