The internal transcribed spacer of ribosomal RNA genes in plant trypanosomes (Phytomonas spp.) resolves 10 groups

The distinction between plant trypanosomatids and opportunistic monoxenous insect trypanosomatids has not been demarcated clearly due to the mass placement of all trypanosomatids isolated from plants into the arbitrary genus Phytomonas spp. The advent of molecular markers has been useful in distinguishing plant trypanosomatids from the rest of the Trypanosomatidae family. Here we have examined the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) locus for classification purposes. This region contains two distinct ITSs flanked by the small subunit and large subunit of ribosomal RNA genes and separated by the 5.8S ribosomal RNA gene. Sequences within the 5.8S ribosomal RNA gene and in the ITS sequences can serve as specific markers for several of the Phytomonas groups. Microsatellite sequences were identified in Phytomonas spp. in both ITS regions. Several classes of microsatellites were seen, with inter-isolate variation that has potential for future use. Maximum Likelihood analysis of the ITS sequences of 20 Phytomonas isolates representing the eight defined groups and a few unclassified isolates revealed a total of 10 distinct subgroups within our collection, of which two are new. The ITS region, which includes the 5.8S sequence, is a robust marker for the subdivisions within the genus Phytomonas spp.     

Large differences in the genome organization of different plant Trypanosomatid parasites (Phytomonas spp.) reveal wide evolutionary divergences between taxa

All currently known plant trypanosomes have been grouped in the genus Phytomonas spp., although they can differ greatly in terms of both their biological properties and effects upon the host. Those parasitizing the phloem sap are specifically associated with lethal syndromes in Latin America, such as, phloem necrosis of coffee, ‘Hartrot’ of coconut and ‘Marchitez sorpresiva’ of oil palm, that inflict considerable economic losses in endemic countries. The genomic organization of one group of Phytomonas (D) considered as representative of the genus has been published previously. The present work presents the genomic structure of two representative isolates from the pathogenic phloem-restricted group (H) of Phytomonas, analyzed by pulsed field gel electrophoresis followed by hybridization with chromosome-specific DNA markers. It came as a surprise to observe an extremely different genomic organization in this group as compared with that of group D. Most notably, the chromosome number is 7 in this group (with a genome size of 10 Mb) versus 21 in the group D (totalling 25 Mb). These data unravel an unsuspected genomic diversity within plant trypanosomatids, that may justify a further debate about their division into different genera.     

Halophilic Vibrio spp. associated with hard clams (Mercenaria spp.) from the Calabar river estuary

One hundred and ten hard clams (Mercenaria spp.) harvested from the Calabar river estuary were examined for total platable heterotrophic bacteria and Vibrio spp. in their mantle fluids using estuarine salts agar and thiosulphate citrate bile salts sucrose agar plates respectively. The mean counts of heterotrophic bacteria and vibrios were 7.9 x 10(6) organisms/ml and 2.5 x 10(2) vibrios/ml respectively. The rate of vibrio infection was 58.2%. Of the clams positive for vibrios, 54 (84%) harboured dual infections (V. alginolyticus and V. parahaemolyticus) of the moderate grade (greater than or equal to 10(3) to 10(5) vibrios/ml). Single infections due to V. alginolyticus or V. parahaemolyticus, found in 16% of clams, were either low (less than 10(3) vibrios/ml), moderate (greater than or equal to 10(3) to 10(5) vibrios/ml), or high (greater than 10(5) vibrios/ml). Dual infections only were detected in clams with mantle fluid volumes greater than 30 ml.     

Effect of resistant starch on the cooking quality of yam (Dioscorea spp.) and cassava (Manihot esculenta) based paste products

Total starch (TS) and resistant starch (RS) contents in pasty edible product of mealy and hard cooking tubers of three yam varieties and four cassava varieties were determined to evaluate their contribution in their cooking quality. TS and RS contents appeared as the main components in determining yam cooking quality. Mealy cooking yam varieties were characterized by a significant higher TS content (75.2 ± 7.7 g/100 g d.m.) and lower RS content (13.8 ± 3.4 g/100 g d.m.) than hard cooking yam varieties, which, in contrast, contained less TS (61.7 ± 12.1 g/100 g d.m.) and particularly high RS (21.8 ± 9.9 g/100 g d.m.), possibly as a consequence of the prevalence of large granules (35–40 μm) observed by light microscope. Conversely, TS and RS contents appeared not determinant on the cooking quality of cassava. Moreover, higher amylose contents were associated with substantially elevated percentages of RS in yam and cassava, and high RS content in samples modulates their pasting properties by reducing the peak viscosity and the breakdown and requiring higher temperature and longer time to the peak.     

克罗诺杆菌种间鉴定recN基因方法建立

目的 建立一种基于重组和修复蛋白基因(recN)的克罗诺杆菌种间鉴定方法,将不同来源的克罗诺杆菌分离株鉴定到种。方法 扩增recN基因全长序列,选取不同长度的recN基因片段,用MEGA 4.0软件对克罗诺杆菌8个参考菌株进行聚类分析,确定克罗诺杆菌种间鉴定可信度高、序列较短的片段;设计并合成该片段的引物,以8株参考菌株作为参照,构建44株克罗诺杆菌实验菌株的聚类分析图,并用生化反应鉴定对聚类结果进行佐证。结果 基于recN基因上一段640 bp的片段可对克罗诺杆菌不同种的菌株进行区分;以8株参考菌株在聚类图上的位置作为参考,根据遗传距离的远近,44株分离菌中有37株阪崎克罗诺杆菌,3株丙二酸盐阳性克罗诺杆菌,3株苏黎世克罗诺杆菌,1株尤尼沃斯克罗诺杆菌,与生化反应鉴定结果一致。结论 该方法与生化鉴定和基于recN全基因方法相比简便快速,PCR扩增后,一次测序反应就可以将克罗诺杆菌鉴定到种。     

Virulence factor-activity relationships (VFAR) with specific emphasis on Aeromonas species (spp.)

The human population most commonly inflicted with Aeromonas infection includes young children, the elderly and immunocompromised individuals. Importantly, the isolation rate of Aeromonas species from children suffering from diarrhea is similar in developing and developed countries. It is becoming clear that only a small subset of Aeromonas species belonging to a particular hybridization group causes disease in humans. Human infections with this pathogen occur by consuming contaminated food and water. Aeromonas species were isolated from wounds of patients during the tsunami in southern Thailand. Further, increased numbers of this pathogen were recovered from floodwater samples during Hurricane Katrina in New Orleans. Among various species of Aeromonas, A. hydrophila, A. caviae and A. veronii biovar sobria are mainly responsible for causing disease in humans. Our laboratory has isolated various virulence factors from a diarrheal isolate SSU of A. hydrophila and molecularly characterized them. In addition to various virulence factors produced by Aeromonas species, the status of the immune system plays an important role in inducing disease by this pathogen in the host. Taken together, we have made significant advances in better understanding the pathogenesis of Aeromonas infections, which will help in differentiating pathogenic from non-pathogenic aeromonads. This review covers virulence aspects of a clinical isolate of A. hydrophila.     

The incidence and significance of salmonella carriage by gulls (Larus spp.) in Scotland.

Salmonella carriage in 5888 gulls sampled by cloacal lavage was found to be 7.8%. Marked geographical and seasonal differences in carriage rates were found. These differences appeared to be associated with human population density and seasonal differences in the reported incidence of human salmonellosis. The maximum duration of salmonella excretion in 17 laboratory-maintained gulls was 4 days and the number of salmonellae excreted was never more than 170 per gram of faeces. On the basis of this study it is suggested that gulls are not important factors in the aetiology of human salmonellosis.     

High-antibacterial activity of Urtica spp. seed extracts on food and plant pathogenic bacteria

The aim of this study was to comparatively evaluate antibacterial activities of methanol (MetOH) and aqueous (dw) leaf (L), root (R) and seed (S) extracts of Urtica dioica L. (Ud; stinging nettle) and Urtica pilulifera L. (Up; Roman nettle) on both food- and plant-borne pathogens, with total phenolic contents and DPPH radical scavenging activities (DRSA). MetOH extracts of leaves and roots of U. dioica had the highest DRSA. Extracts with high antibacterial activity were in the order Up-LMetOH (13/16) > Ud-SMetOH (11/16) > Up-SMetOH (9/16). Results obtained with Up-SMetOH against food spoiling Bacillus pumilus, Shigella spp. and Enterococcus gallinarum with minimum inhibitory concentrations (MICs) in 128–1024 μg/ml range seem to be promising. Up-SMetOH also exerted strong inhibition against Clavibacter michiganensis with a considerably low MIC (32 μg/ml). Ud-SMetOH and Up-LMetOH were also effective against C. michiganensis (MIC = 256 and 1024 μg/ml, respectively). Ud-SMetOH and Ud-RMetOH had also antimicrobial activity against Xanthomonas vesicatoria (MIC = 512 and 1024 μg/ml, respectively). Results presented here demonstrate high-antibacterial activity of U. pilulifera extracts and U. dioica seed extract against phytopathogens for the first time, and provide the most comprehensive data on the antibacterial activity screening of U. pilulifera against food-borne pathogens. Considering limitations in plant disease control, antibacterial activities of these extracts would be of agricultural importance.     

Piranhas (Serrasalmus spp.) as markers of mercury bioaccumulation in Amazonian ecosystems

Mercury (Hg) concentration in fish depends on feeding strategies and age/size within the species as well as on water parameters related to acidity and Hg speciation. We chose two species of piranhas (Serrasalmus aff. eigenmanni and Serrasalmus rhombeus) to test their suitability as markers of Hg bioaccumulation. The results of Hg concentrations in piranhas of the Rio Negro, with no history of gold-mining activity, are similar to other Amazonian rivers with intensive gold mining. An increase in water Hg associated with low pH favored higher mean Hg concentrations in the two species. S. rhombeus in this habitat showed a consistently higher Hg concentration than S. eigenmanni. This result was attributed to fish size because of differences in correlation coefficient between S. rhombeus (r = 0.4443; P < 0.0001) and S. eigenmanni (r = 0.1520; P = 0.0135). Matching for fish weight resulted in comparable ranges of Hg concentrations between the two species.     

Genetic characterization and phylogenetic relationships based on 18S rRNA and ITS1 region of small form of canine Babesia spp. from India

Canine babesiosis is a vector borne disease caused by intra-erythrocytic apicomplexan parasites Babesia canis (large form) and Babesia gibsoni (small form), throughout the globe. Apart from few sporadic reports on the occurrence of B. gibsoni infection in dogs, no attempt has been made to characterize Babesia spp. of dogs in India. Fifteen canine blood samples, positive for small form of Babesia, collected from northern to eastern parts of India, were used for amplification of 18S rRNA gene (∼1665 bp) of Babesia sp. and partial ITS1 region (∼254 bp) of B. gibsoni Asian genotype. Cloning and sequencing of the amplified products of each sample was performed separately. Based on sequences and phylogenetic analysis of 18S rRNA and ITS1 sequences, 13 were considered to be B. gibsoni. These thirteen isolates shared high sequence identity with each other and with B. gibsoni Asian genotype. The other two isolates could not be assigned to any particular species because of the difference(s) in 18S rRNA sequence with B. gibsoni and closer identity with Babesia occultans and Babesia orientalis. In the phylogenetic tree, all the isolates of B. gibsoni Asian genotype formed a separate major clade named as Babesia spp. sensu stricto clade with high bootstrap support. The two unnamed Babesia sp. (Malbazar and Ludhiana isolates) clustered close together with B. orientalis, Babesia sp. (Kashi 1 isolate) and B. occultans of bovines. It can be inferred from this study that 18S rRNA gene and ITS1 region are highly conserved among 13 B. gibsoni isolates from India. It is the maiden attempt of genetic characterization by sequencing of 18S rRNA gene and ITS1 region of B. gibsoni from India and is also the first record on the occurrence of an unknown Babesia sp. of dogs from south and south-east Asia.     

Rational development of prophylactic HIV vaccines based on structural and regulatory proteins.

The severity of the AIDS epidemic clearly emphasises the urgent need to expedite HIV vaccine candidates into clinical trials. Prophylactic HIV vaccine candidates have been evaluated in non-human primates. Based on specific proof of principle studies the first phase III clinical studies have recently begun in humans. However, a truly effective HIV vaccine is not yet at hand and many problems related to specific properties of the virus remain to be overcome. Previously proven empirical approaches have largely failed and now rational thinking based on an understanding of immunity to lentiviral infections is needed. This review addresses the scientific problems and complications facing the development of an HIV vaccine as well as the possible strategies currently available to overcome these problems. Recent attention has focussed on identifying the immune correlates and mechanisms of protection from either HIV infection or protection from disease progression. Based on these observations, the logic and rational behind the development of multiple component vaccine strategies are highlighted.     

Investigation on the mineral contents of capers (Capparis spp.) seed oils growing wild in Turkey

Minor and major mineral contents of seed oils of Capparis ovata Desf. var. canescens (Coss.) Heywood and Capparis spinosa var. spinosa used as pickling products in Turkey were determined by inductively coupled plasma atomic emission spectrometry. The seed oils contained Al, P, Na, Mg, Fe, and Ca, in addition to fatty acids. The highest mineral concentrations measured were 14.91-118.81 mg/kg Al, 1,489.34-11,523.74 mg/kg P, 505.78-4,489.51 mg/kg Na, 102.15-1,655.33 mg/kg Mg, 78.83-298.14 mg/kg Fe, and 1.04-76.39 mg/kg Ca. The heavy metal concentrations were less than the limit of detection in all oil samples. The results may also be useful for the evaluation of nutritional information.     

The incidence and significance of salmonella carriage by gulls (Larus spp.) in Scotland

Salmonella carriage in 5888 gulls sampled by cloacal lavage was found to be 7.8%. Marked geographical and seasonal differences in carriage rates were found. These differences appeared to be associated with human population density and seasonal differences in the reported incidence of human salmonellosis. The maximum duration of salmonella excretion in 17 laboratory-maintained gulls was 4 days and the number of salmonellae excreted was never more than 170 per gram of faeces. On the basis of this study it is suggested that gulls are not important factors in the aetiology of human salmonellosis.     

Detection of Rickettsia spp. and Anaplasma phagocytophilum in Ixodes ricinus ticks in a region of Middle Germany (Thuringia)

Rickettsia spp. and Anaplasma spp. are regarded as potentially emerging tick-borne pathogens, but so far data on prevalence rates in questing ticks and reports on human diseases in several parts of Europe are rarely available.In this study, 430 nymphs and 570 adult Ixodes (I.) ricinus ticks were collected from a frequently visited forest region of Thuringia (Zeitzgrund, near Stadtroda) in 2006 (n=506) and 2007 (n=494). Individual ticks were investigated for a part of the citrate synthase gene (gltA) of Rickettsia spp. and the 16S rRNA gene of Anaplasma phagocytophilum. Positive amplicons were identified with restriction fragment length polymorphism (RFLP) and/or sequencing. Overall, 14.7% (147/1000) of investigated ticks were infected with Rickettsia spp. After sequencing of 64/147 positive amplicons R. helvetica (29/64) was detected predominantly. Prevalence varied in different developmental stages between 9.3% (40/430) in nymphs and 18.8% (107/570) in adults. A. phagocytophilum-specific DNA was detected in 5.4% (54/1000) of ticks with an infection rate of 4.7% (20/430) in nymphs and 6.0% (34/570) in adults. In 1% (10/1000) of ticks coinfections with Rickettsia spp. and A. phagocytophilum were found. Our study provides interesting insights into the circulation and cocirculation of different rickettsial species and A. phagocytophilum in the same biotope.     

The effects of essential oils and aqueous tea infusions of oregano (Origanum vulgare L. spp. hirtum), thyme (Thymus vulgaris L.) and wild thyme (Thymus serpyllum L.) on the copper-induced oxidation of human low-density lipoproteins

In this study, the antioxidative capacity effect of essential oils and aqueous tea infusions obtained from oregano, thyme and wild thyme on the oxidation susceptibility of low-density lipoproteins (LDL) has been studied. The results indicate a dose-dependent protective effect of the tested essential oils and aqueous tea infusions on the copper-induced LDL oxidation. The protective effect of essential oils is assigned to the presence of phenolic monoterpenes, thymol and carvacrol, which are identified as the dominant compounds in these essential oils. The strong protective effect of aqueous tea infusions is proposed to be the consequence of large amounts of polyphenols, namely rosmarinic acid and flavonoids (quercetin, eriocitrin, luteolin-7-O-glucoside, apigenin-7-O-glucoside, luteolin, apigenin), with the most pronounced effect in the case of oregano. These findings may have implications for the effect of these compounds on LDL in vivo.