Use of plasmid profiles to detect changes in strains of Staphylococcus aureus during poultry processing

The plasmid profiles of Staphylococcus aureus strains isolated at different stages in three poultry processing plants have been examined. Changes in profiles were seen in two plants after the plucking stage and the appearance of these new profiles correlated with the presence of an endemic strain, as suggested previously by increases in bacterial counts and changes in biotypes at the same stage. A third plant in which such changes did not occur showed no change in profiles. Plasmid profiles are therefore a rapid and sensitive method for distinguishing endemic strains within a plant from the flora of the incoming birds. Certain profiles also appeared to correspond with particular biotypes and certain phage types.     

Plasmid profiles as indicators of the source of contamination of Staphylococcus aureus endemic within poultry processing plants

A total of 530 strains of Staphylococcus aureus were isolated from the defeathering machinery of a chicken processing plant and from neck skin samples of carcasses at different stages of processing in two visits 4 weeks apart. Eleven different plasmid profiles were detected in the isolates, eight being common to both visits. The plasmid profiles of the strains forming the majority of the population on the freshly slaughtered birds were rarely present in the strains isolated from the pluckers (except at the entry to the first plucker) and were present in only a small proportion of the strains isolated from carcasses after plucking. However, the profiles from the strains isolated from the pluckers on both visits were different from those forming the majority of the population on the incoming birds but formed the major part of the carcass flora after plucking, suggesting that such strains were endemic. These strains were found as a small proportion of the isolates made from the incoming birds, suggesting that this was the route by which the endemic strains were introduced into the plant. Such endemic strains exhibited a clumping growth, even in liquid shake culture, which may have made it easier for them to become established on the pluckers and to resist cleaning and disinfection. This clumping phenotype was correlated with the presence of a 7.5-megadalton plasmid.     

Plasmid profiles as indicators of the source of contamination of Staphylococcus aureus endemic within poultry processing plants.

A total of 530 strains of Staphylococcus aureus were isolated from the defeathering machinery of a chicken processing plant and from neck skin samples of carcasses at different stages of processing in two visits 4 weeks apart. Eleven different plasmid profiles were detected in the isolates, eight being common to both visits. The plasmid profiles of the strains forming the majority of the population on the freshly slaughtered birds were rarely present in the strains isolated from the pluckers (except at the entry to the first plucker) and were present in only a small proportion of the strains isolated from carcasses after plucking. However, the profiles from the strains isolated from the pluckers on both visits were different from those forming the majority of the population on the incoming birds but formed the major part of the carcass flora after plucking, suggesting that such strains were endemic. These strains were found as a small proportion of the isolates made from the incoming birds, suggesting that this was the route by which the endemic strains were introduced into the plant. Such endemic strains exhibited a clumping growth, even in liquid shake culture, which may have made it easier for them to become established on the pluckers and to resist cleaning and disinfection. This clumping phenotype was correlated with the presence of a 7.5-megadalton plasmid.     

Comparison of outer membrane protein profiles of Vibrio vulnificus biotypes 1 and 2

Abstract The outer membrane proteins of 17 Vibrio vulnificus biotype 2 strains from Japanese and European cels, and 12 biotype 1 strains from clinical and environmental sources have been compared. The overall profile in both biotypes was similar, and a major protein band of molecular mass 36 kDa was detected in the majority of the strain. Differences in the minor bands allowed differentiation of strains from different origins, suggesting that outer membrane protein profiles could be useful as epidemiological markers in the species V. vulnificus . Immunoblotting with antisera to whole cells of selected strains of biotypes 1 and 2 showed a strong antigenic response to outer membrane proteins 66, 60, 48, 46 and 44 kDa; these were common to all strains examined, independent of their biotypes and origins. These results demonstrate the presence of antigenically related outer membrane proteins in both biotypes of V. vulnificus .     

Plasticity of reproductive traits responding to variation in light availability at the rosette stage of the first year in a strict biennial,Pedicularis torta,from a field on the Qinghai–Tibet Plateau,China

Light is a fundamental heterogeneous environmental factor for plants and often varies at both spatial and temporal scales. In the present study, we carried out a shading experiment to investigate the effect of variable light availability at the rosette stage of the first year in the strict biennial species Pedicularis torta (an endemic species of the Qinghai‐Tibet Plateau) on reproductive traits (i.e. total number of flowers per plant, total number of fruits per plant/total number of flowers per plant, the number of seeds per fruit, mean individual seed mass and estimation of the total number of seeds per plant, plant size at maturity in the second year and on the relationships between reproductive traits and plant size at this stage). We found that light availability affected most of the reproductive traits (except for mean individual seed mass), plant size at maturity in the second year, and the relationship between the total number of flowers per plant and plant size at this stage. Our results indicate that reproductive traits respond to changes in light availability during the rosette plant stage.     

Plasmids of Staphylococcus aureus associated with live and processed poultry

A series of 23 strains of Staphylococcus aureus originally isolated from processed poultry was screened for the presence of plasmids. Plasmids were more common in strains of Staph. aureus characteristically associated with live poultry than with strains endemic in poultry plants and strains of human origin. Two plasmids with sizes of 1.65 and 18.2 kilobase pairs (kBp) were present in three strains considered typical of Staph. aureus forma specialis 'altilis' and two plasmids with sizes of 1.65 and 17 kBp were present in three of four strains of Staph. aureus var. gallinae. A 1.65 kBp plasmid was present in all seven strains of these poultry biotypes and in three of 14 'endemic' strains. All the 1.65 kBp plasmids were shown by blot hybridization to share sequence homology. There was also some sequence homology between the 18.2 kBp and 17 kBp plasmids. These results were supported by restriction enzyme digest analyses. A study of cured derivatives of strain PS221 f.sp. 'altilis' suggested that the 18.2 kBp plasmid encoded the genetic determinant(s) responsible for caseolysis. Both the 1.65 and the 18.2 kBp plasmids also exerted an effect on the production of acid from lactose. In no other characteristic did cured strains resemble the plasmid-free 'endemic' strains. This was therefore consistent with the notion that the genetic determinants associated with the cultural characteristics of endemic strains are chromosomally located.     

Mutant genes of plant tubulins as selective marker genes for genetic engineering

This review describes different approaches to employment of new marker genes in selection of transformed plant cells, which are based on the use of mutant tubulin genes from natural plant biotypes and, in prospect, induced plant mutants. The results of studies of plant (biotypes, mutants) resistance to herbicides with antimicrotubular mode of action at molecular and cellular levels were summarized. The reports on the transfer and expression of mutant tubulin genes conferring resistance to amiprophosmethyl (phosphorothioamidate herbicide) and trifluralin (dinitroaniline herbicide) from corresponding Nicotiana plumbaginifolia mutants in related and remote plant species by somatic hybridization methods were analyzed. The results of experiments on transformation of monocotyledonous and dicotyledonous plants by mutant α-tubulin gene conferring resistance to dinitroanilines are described to test the possibility of its use as a marker gene and simultaneously obtaining dinitroaniline-resistant plants.     

二氯喹啉酸诱导稗草EcDnaJ基因表达

DnaJ作为分子伴侣在植物抗逆中起重要作用. 但目前在二氯喹啉酸逆境下,其在抗药性稗草中表达特点却鲜有报道. 本研究采用RACE技术从抗二氯喹啉酸稗草中克隆了1个DnaJ基因, 命名为EcDnaJ1 (GenBank登录号：JX518598), 其cDNA全长为2 154 bp, 开放阅读框为1 350 bp,编码449 个氨基酸, 理论分子量为48.4 kD, 等电点为9.5. 该蛋白质氮端含有1个保守的J结构域, 中部含有4个模式为CxxCxGxG的锌指结构. Real-time PCR分别测定EcDnaJ1在二氯喹啉酸抗性和敏感的稗草生物型苗期叶、根及成株期根、茎、叶和种子中的表达, 在感、抗生物型的相对表达量分别是0.8～20.9和7.4～30.2, 其中在抗性稗草苗期叶片中相对表达量最高为30.2, 而在敏感稗草种子中最低为0.8, 抗性稗草是敏感稗草的1.4～9.2 倍. 受二氯喹啉酸诱导后, 其在感、抗稗草的相对表达量分别为35.8～72.5和84.9～261.9, 在抗性稗草苗期叶片中相对表达量最高为261.9, 而在敏感稗草的种子中相对表达量最低为35.8, 抗性稗草是敏感稗草的2.4～3.6 倍. 诱导前后, 无论是在苗期根和叶中还是成株期的根、茎、叶和种子中, EcDnaJ1表达量均是抗性稗草高于敏感稗草. 抗、感稗草生物型的EcDnaJ1在mRNA水平差异表达暗示,它可能参与了稗草对二氯喹啉酸的抗药性.     

Plasmids of Staphylococcus aureus associated with live and processed poultry

A series of 23 strains of Staphylococcus aureus originally isolated from processed poultry was screened for the presence of plasmids. Plasmids were more common in strains of Staph. aureus characteristically associated with live poultry than with strains endemic in poultry plants and strains of human origin. Two plasmids with sizes of 1·65 and 18·2 kilobase pairs (kBp) were present in three strains considered typical of Staph. aureus forma specialis 'altilis' and two plasmids with sizes of 1·65 and 17 kBp were present in three of four strains of Staph. aureus var. gallinae. A 1·65 kBp plasmid was present in all seven strains of these poultry biotypes and in three of 14 'endemic' strains. All the 1·65 kBp plasmids were shown by blot hybridization to share sequence homology. There was also some sequence homology between the 18·2 kBp and 17 kBp plasmids. These results were supported by restriction enzyme digest analyses. A study of cured derivatives of strain PS221 f.sp. 'altilis' suggested that the 18·2 kBp plasmid encoded the genetic determinant(s) responsible for caseolysis. Both the 1·65 and the 18·2 kBp plasmids also exerted an effect on the production of acid from lactose. In no other characteristic did cured strains resemble the plasmid-free 'endemic' strains. This was therefore consistent with the notion that the genetic determinants associated with the cultural characteristics of endemic strains are chromosomally located.     

Battling the biotypes of balsam: the biological control of Impatiens glandulifera using the rust fungus Puccinia komarovii var. glanduliferae in GB

Impatiens glandulifera, or Himalayan balsam, is a prolific invader of riverine habitats. Introduced from the Himalayas for ornamental purposes in 1839, this annual species has naturalised across Great Britain (GB) forming dense monocultures with negative affects across whole ecosystems. In 2006 a programme exploring biocontrol as an alternative control method was initiated and to date, two strains of the rust fungus Puccinia komarovii var. glanduliferae have been released. To better understand the observed differences in susceptibility of GB Himalayan balsam stands to the two rust strains, inoculation studies were conducted using urediniospores and basidiospores. Experiments revealed large variation in the susceptibility of stands to urediniospores of the two rust strains, with some resistant to both. Furthermore, the infectivity of basidiospores was found to differ, with some stands fully susceptible to the urediniospore stage, being immune to basidiospore infection. Therefore, before further rust releases at new sites, it is necessary to ensure complete compatibility of the invasive stands with both urediniospores and basidiospores. However, for successful control across GB it is essential that plant biotypes are matched to the most virulent rust strains. This will involve additional strains from the native range to tackle those biotypes resistant to the strains currently released.     

Preformed enzyme profiling of Helicobacter pylori and Helicobacter mustelae from human and animal sources

A total of 126 strains of Helicobacter pylori from human and animal (monkey, baboon and pig) gastric mucosa, and four strains of H. mustelae were biotyped using preformed enzyme profiles (API Zym). The strains were from 10 countries and they were predominantly biotype II (85%). The other three biotypes, which were less frequently encountered, were detected with similar frequency (4–6%). There was no evidence of geographical or host-associated biotype differences. Reference strains for each of the biotypes are available from the NCTC for inclusion in future studies.     

Profiling a besieged flora: endemic and threatened plants of the Cape Peninsula, South Africa

The Cape Peninsula (area: 471 km²), situated at the south-western extremity of the Cape Floristic Region, has exceptionally high plant species richness (2285 species and infraspecific taxa) and numbers of endemic (90; 88 species and two infraspecific) and threatened (141; 138 species and three infraspecific) taxa (termed species from here on). This biodiversity is threatened by urban development and the spread of invasive alien plants. Peninsula endemics are concentrated in a few, predominantly species-rich families and these correspond well with endemic-rich families in other areas of the Cape Floristic Region. A high level of similarity exists between families with threatened and families with endemic species. A frequency analysis of the biological traits of both endemic and threatened species shows that low growing, ant-dispersed shrubs are over-represented in both groups. Endemics are most likely to be non-sprouters, but threatened plants do not have a specific post-fire regeneration strategy. Threatened species have higher frequencies of geophytes, sprouters and wind-dispersed species compared to endemic species. Numbers of endemic and threatened species are not randomly distributed with regard to occurrence in vegetation types and patterns are similar for both groups. The habitat and biological profiles of both endemic and threatened species suggest that they are highly vulnerable to extinction as a result of increasing rates of alien plant infestation, urbanization and inappropriate fire regimes.     

Plant mutant tubulin genes as marker selective genes for genetic engineering

The approaches for new marker genes usage in selection of transformed plant cells, which are based on using mutant tubulin genes from natural plant biotypes and, in perspective, from induced plant mutants have been considered. The results of investigations of plant (biotypes, mutants) resistance to herbicides with antimicrotubular mode of action on molecular and cellular levels have been summarized. The reports dealing with study the transferring and the expression of mutant tubulin genes conferring resistance to amiprophosmethyl (phosphorothioamidate herbicide) and to trifluralin (dinitroaniline herbicide) from corresponding N. plumbaginifolia mutants into related and remote plant species by somatic hybridisation methods have been analyzed. The results of experiments on monocotyledonous and dicotyledonous. plant transformation by mutant alpha-tubulin gene conferring resistance to dinitroanilines are described to test the possibility of its using as a marker gene with obtaining, at the same time, a dinitroaniline-resistant plants.     

Differences in escape behavior between pea aphid biotypes reflect their host plants’ palatability to mammalian herbivores

Phytophagous insects have evolved traits that help them avoid predation risks, traits that may be affected by characteristics of the host plant. Since most phytophagous insects have narrow host ranges, we expect differences in risk avoidance between plant-specialized populations of several closely related insect lineages. To test this hypothesis, we used the pea aphid (Acyrthosiphon pisum), which forms a complex of about 15 biotypes, each adapted to one or a few species of legume plants (Fabaceae). We examined the differences in defensive behaviors of 38 clones from 13 distinct plant-specialized biotypes of pea aphids. We exposed mature aphids to simulated breath of a mammalian herbivore, a cue that causes part of the aphids in a colony to immediately drop off the plant to avoid incidental ingestion during mammal feeding. Dropping tendency varied substantially between biotypes (15–93% average rates). Dropping rates of a certain biotype of aphid reflected their host’s palatability to mammalian herbivores, with ∼80–90% rates in fodder and pasture plants and ∼15–40% dropping in inedible plants. The dropping tendency showed no correlation with walking ability (tarsal & body length), nor with the tendency to escape in response to the alarm pheromone released by conspecifics in response to arthropod enemies. The specialization on a specific host plant brings with it particular selective pressures, and it seems that the palatability of the plants to mammals promotes behavioral divergence between biotypes, reinforcing diversification through ecological divergence.     

New Coffee Plant-Infecting Xylella fastidiosa Variants Derived via Homologous Recombination

Xylella fastidiosa is a xylem-limited phytopathogenic bacterium endemic to the Americas that has recently emerged in Asia and Europe. Although this bacterium is classified as a quarantine organism in the European Union, importation of plant material from contaminated areas and latent infection in asymptomatic plants have engendered its inevitable introduction. In 2012, four coffee plants (Coffea arabica and Coffea canephora) with leaf scorch symptoms growing in a confined greenhouse were detected and intercepted in France. After identification of the causal agent, this outbreak was eradicated. Three X. fastidiosa strains were isolated from these plants, confirming a preliminary identification based on immunology. The strains were characterized by multiplex PCR and by multilocus sequence analysis/typing (MLSA-MLST) based on seven housekeeping genes. One strain, CFBP 8073, isolated from C. canephora imported from Mexico, was assigned to X. fastidiosa subsp. fastidiosa/X. fastidiosa subsp. sandyi. This strain harbors a novel sequence type (ST) with novel alleles at two loci. The two other strains, CFBP 8072 and CFBP 8074, isolated from Coffea arabica imported from Ecuador, were allocated to X. fastidiosa subsp. pauca. These two strains shared a novel ST with novel alleles at two loci. These MLST profiles showed evidence of recombination events. We provide genome sequences for CFBP 8072 and CFBP 8073 strains. Comparative genomic analyses of these two genome sequences with publicly available X. fastidiosa genomes, including the Italian strain CoDiRO, confirmed these phylogenetic positions and provided candidate alleles for coffee plant adaptation. This study demonstrates the global diversity of X. fastidiosa and highlights the diversity of strains isolated from coffee plants.     

NONRANDOM GENOTYPIC ASSOCIATIONS IN A LEGUME—BRADYRHIZOBIUM MUTUALISM

Genetically divergent lineages often coexist within populations of the annual legume Amphicarpaea bracteata. At one site dominated by two such lineages (termed biotypes “C” and “S”), isolates of root-nodule bacteria (Bradyrhizobium sp.) were sampled from both hosts and analyzed by enzyme electrophoresis. Symbiont populations on the two plant biotypes were highly distinct. Out of 15 bacterial multilocus genotypes detected (among 51 isolates analyzed), only one was shared in common by the two plant biotypes. Cluster analysis revealed three bacterial lineages (designated I, II, and III), with lineage I found exclusively on biotype C plants, and the two other lineages almost completely restricted to biotype S hosts. Laboratory inoculation tests indicated that lineage I bacteria were strictly specialized on biotype C hosts, forming few or no nodules on plants of the other host biotype. Bacterial lineages II and III were capable of forming nodules on both kinds of plants, but nodule numbers were often significantly higher on biotype S hosts. The nonrandom association between plant and bacterial lineages at this site implies that genetic diversity of hosts is an important factor in the maintenance of polymorphism within the symbiont population.     

Plasmid profiles of Lactobacillus plantarum spp. found as contaminants in Hemerocallis plant tissue cultures

Plasmid profiles of 30 strains of Lactobacillus plantarum isolated from 3-year-old tissue cultures and surface sterilized stem sections of glasshouse grown plants of three different varieties of Hemerocallis were compared to pinpoint the source of Lact. plantarum contamination in plant tissue cultures. Since the profiles of strains isolated from in vitro and in vivo plant material were generally identical, it is thought that the source of Lact. plantarum contamination is the plant material used to initiate plant tissue cultures.     

Genetic diversity of the submerged macrophyte Hydrilla verticillata (L. f.) Royle in a river system in Japan

The genetic diversity of Hydrilla verticillata was studied in the Kako River system, Hyogo Prefecture, southwestern Japan, including some of its tributaries. Sex expression (monoecy or dioecy), ploidy level (diploid or triploid), and isoenzyme phenotypes were investigated for plant samples collected from 51 sites along the water course. Monoecious plants occurred at 10 sites and dioecious plants at 47 sites. Among dioecious plants, diploid and triploid plants occurred at 1 and 46 sites, respectively. Seven multienzyme phenotypes (MEPs) were recognized by electrophoretic analysis among dioecious triploid plants. The distribution pattern of nine biotypes based on sex expression, ploidy level, and MEPs suggested the possibility of ecological differentiation among different biotypes. The implications of genetic diversity demonstrated in this study were discussed in relation to the conservation strategy of biodiversity in a river system. Received: April 12, 1999 / Accepted: July 7, 1999     

Comparison of performance on different host plants between the B biotype and a non-B biotype of Bemisia tabaci from Zhejiang, China

The capacity of the B biotype of the whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae), to invade has often been linked to its presumably wider host range than the non‐B indigenous biotypes. However, there are few experimental studies of the relative performance of the B biotype and non‐B biotypes on different host‐plant species. Here, we compared the performance of the B biotype and an indigenous non‐B biotype (China‐ZHJ‐1) of B. tabaci from Zhejiang, China on five commonly cultivated host plants, each from a different family: cotton, tobacco, cabbage, squash, and kidney bean. We also examined the effect of rearing host plants on the performance of the B biotype. Overall, the performance of the B biotype on the five species of plants was much better than that of the indigenous non‐B population. On tobacco, cabbage, and kidney bean, no individuals of ZHJ‐1 completed development to adulthood, whereas the B biotype developed successfully from egg to adult on all three plants. On squash, the B biotype survived better, developed to adulthood earlier and had a higher fecundity than ZHJ‐1. The two biotypes performed more equally on cotton, but even on this plant the B biotype female adults lived nearly twice as long as that of ZHJ‐1 and may have realized a higher life‐time fecundity. The B biotype also showed a substantial capacity to acclimatize to alternative host plants for improved survival and reproduction, on both highly suitable and marginally suitable host plants. We conclude that the host range of the B biotype of B. tabaci may be much wider than those of some indigenous biotypes, and this advantage of the B biotype over the non‐B biotypes may assist in its invasion and displacement of some indigenous biotypes in the field.