Characterization of Pasteurella multocida isolates from wetland ecosystems during 1996 to 1999

We cultured 126 Pasteurella multocida isolates, 92 from water and 34 from sediment samples collected from wetlands in the Pacific and Central flyways of the United States between 1996 and 1999. Most (121) of the isolates were P. multocida serotype 1, but serotypes 3, 3/4, 10, and 11 were also found. Many (82) of the isolates were further characterized by DNA fingerprinting procedures and tested in Pekin ducks for virulence. Almost all the serotype 1 isolates we tested caused mortality in Pekin ducks. Serotype 1 isolates varied in virulence, but the most consistent pattern was higher mortality in male ducks than in females. We found no evidence that isolates found in sediment vs. water, between Pacific and Central flyways, or during El Ni?o years had consistently different virulence. We also found a number of non-serotype 1 isolates that were avirulent in Pekin ducks. Isolates had DNA fingerprint profiles similar to those found in birds that died during avian cholera outbreaks.     

重症监护病房产ESBLs菌的基因分型

目的了解深圳市人民医院重症监护病房分离菌超广谱β-内酰胺酶（ESBLs）的检出率及其基因型分布情况。方法收集来自重症监护病房大肠埃希菌和肺炎克雷伯菌分离株48株,采用CLSI推荐的表型确证方法筛选出ESBLs株,并利用PCR及DNA测序法分析产酶菌株的ESBL基因型。结果（1）48分离株菌中共检出产ESBLs菌24株,阳性率为50.0%。（2）产酶菌中93.8%（15/16）的大肠埃希菌和87.5%（7/8）的肺炎克雷伯菌分别检出CTX-M基因;其中72.7%（16/22）为CTX-M-14。6株肺炎克雷伯菌检出SHV基因,其中3株为SHV-11型,另3株为SHV-12型,6株含SHV基因的肺炎克雷伯菌中5株合并CTX-M基因。而所有大肠埃希菌株均未检出SHV基因。所有产酶菌中,分别有10株大肠埃希菌和2株肺炎克雷伯菌检出TEM-1基因,其中1株大肠埃希菌只检出TEM-1基因,未检出SHV型或CTX-M型基因。结论重症监护病房分离菌ESBLs检出率高,以CTX-M-14为主要基因型。     

Fusarium solani species complex isolates conspecific with Fusarium solani f. sp. cucurbitae race 2 from naturally infected human and plant tissue and environmental sources are equally virulent on plants, grow at 37 degrees C and are interfertile

In a previous taxonomic study based on multilocus sequencing of Fusarium from clinical specimens and hospital environments, the most common lineage was Fusarium solani species complex group 1 (FSSC 1) which is conspecific with F. solani f. sp. cucurbitae race 2, a pathogen of cucurbit fruits. The aims of our study were to determine if clinical and environmental isolates of FSSC 1 are plant pathogens and members of the same biological species as cucurbit isolates, and to determine if all isolates can germinate, grow and sporulate at 37 degrees C. Isolates from the different sources did not differ in virulence on zucchini fruits. All FSSC 1 isolates were pathogenic and produced more rot than FSSC isolates from plant hosts other than cucurbits. Both mating types were found among isolates from each of the sources, and all isolates were sexually compatible with cucurbit isolates. All isolates germinated, grew and sporulated at 37 degrees C. This is the first report in which plant pathogenicity has been verified for a collection of human clinical isolates. Our data are consistent with the hypothesis that all FSSC 1 isolates, regardless of source, are a single biological species, equally virulent plant pathogens and tolerant of the human body temperature.     

Antibiotic resistance and virulence properties of Pseudomonas aeruginosa strains from mechanically ventilated patients with pneumonia in intensive care units: comparison with imipenem-resistant extra-respiratory tract isolates from uninfected patients

We investigated the epidemiology of antibiotic resistance and virulence properties among Pseudomonas aeruginosa clinical isolates collected in 1999 from patients hospitalized in the intensive care units of the centre hospitalier d'Orléans, in France. We compared the totality of the strains from mechanically ventilated patients with pneumonia (33 non-duplicate isolates, group 1) to 15 randomly chosen, imipenem-resistant, extra-respiratory tract isolates, collected from non-infected patients hospitalized in the same units (group 2). The isolates were serotyped, typed by random amplified polymorphic DNA (RAPD), and screened for their pneumocyte cell adherence, cytotoxicity, and antibiotic resistance. A total of 35 RAPD profiles were found, and only two profiles were encountered in both groups, demonstrating a high genetic diversity. 84.8% of the group 1 and 93.3% of the group 2 isolates adhered to A549 cells. Three non-exclusive adhesive patterns were observed: a diffuse adhesion in 38 isolates, a localized adhesion in 14 isolates, and an aggregative adhesion in seven isolates. 78.8% of the group 1 and 93.3% of the group 2 isolates were cytotoxic. Considering all 48 isolates, there was a strong and statistically significant correlation between cytotoxicity and adherence. Among the three dominant serotypes, O:12 isolates were in majority avirulent, but the great majority of O:1 and all the O:11 isolates were found adherent and cytotoxic. Gentamicin was the least active antibiotic for both groups, and ceftazidime was the most active antibiotic for group 1 and amikacin for group 2. The penicillinase production phenotype was significantly correlated with a decrease in P. aeruginosa virulence.     

Fertility status and distribution of mating type alleles of the rice blast fungus, Magnaporthe grisea in northern Iran

This study was carried out using 155 monoconidial isolates collected from different areas of two major rice growing provinces in northern Iran, including 94 isolates from Guilan and 59 isolates from Mazandaran. Among 94 isolates from Guilan, 92 and two isolates recovered from rice and crabgrass (Digitaria sp.), respectively. All 61 rested isolates from Mazandaran were recovered from rice. All isolates were evaluated for in vitro sexual fertility and mating type status by pairing with Mat 1-1 and Mat 1-2 fertile standard hermaphrodite isolates including Br48 and Th12 (Mat 1-1) and KA9 and TH16 (Mat 1-2). Of 155 isolates, 98 (63.2%) were fertile and 57 (36.8%) were infertile and produced no perithecium when mated with standard isolates. Among 98 fertile isolates, 96 isolates were identified as Mat 1-1 and two isolates as Mat 1-2. All Mat 1-1 isolates were obtained from rice and two Mat 1-2 isolates obtained from crab grass. No Mat 1-2 isolate was identified from rice in this study. Both mating types were found in Guilan but all isolates recovered from Mazandaran were identified as Mat 1-1. Male fertility predominated in fertile Mat 1-1 and Mat 1-2 isolates from all sampling sites in northern Iran, and no female fertility was detected. This is the first report of existence of Mat 1-2 allele in Magnaporthe grisea population in Iran.     

Distribution and Characterization of Bacillus thuringiensis on the Phylloplane of Species of Piper (Piperaceae) in Three Altitudinal Levels

Bacillus thuringiensis is found naturally on the phylloplane. In this study 35 samples from 13 species of the genus Piper (Piperaceae) were collected from three altitudinal levels located between 1800 and 2900 m above sea level in the Colombian Andean forest of Central Cordillera. Two hundred and fifty-six isolates of B. thuringiensis were obtained from 74% of the samples studied. B. thuringiensis index (number of isolates of B. thuringiensis/number of isolates of sporulated bacilli) was 0.2. The isolates were characterized by crystal morphology, the presence of cry genes by PCR, and toxicity against insects. Fifty-five percent of the isolates found presented bipyramidal-crystal morphology, and 42% had round-crystal morphology. Seventy percent of the isolates amplified cry1 [cry one] genes (generally toxic to lepidopterans); 41.4% amplified cry4 and/or cry11 [cry eleven] genes (generally toxic to dipterans), and none of the isolates amplified cry3 genes (generally toxic to coleopterans). The most abundant genotype of cry genes (54.7% of the total) was cry1Aa, cry1Ab, cry1Ac, cry1Ad, and cry1B. From the total isolates found, 7.8% presented both cry1 and cry11 genes, and five isolates (2.0%) harbored cry1, cry4, and cry11 genes; all these isolates were toxic to Culex quinquefasciatus (Diptera) but not to Spodoptera frugiperda (Lepidoptera). To our knowledge, these genotypes have not been previously reported. Overall, almost 60% of the isolates were toxic to S. frugiperda, and a little more than 40% of the isolates were toxic to C. quinquefasciatus. The populations of viable vegetative cells and spores per unit area were estimated and studied statistically. No significant differences in the number of B. thuringiensis isolates per cm2 of leaf among the three altitudinal levels were found, nor were they found among the different Piper species evaluated. This study increases the knowledge of the ecology of B. thuringiensis.     

Molecular phylogeny of the psittacid herpesviruses causing Pacheco's disease: correlation of genotype with phenotypic expression

Fragments of 419 bp of the UL16 open reading frame from 73 psittacid herpesviruses (PsHVs) from the United States and Europe were sequenced. All viruses caused Pacheco's disease, and serotypes of the European isolates were known. A phylogenetic tree derived from these sequences demonstrated that the PsHVs that cause Pacheco's disease comprised four major genotypes, with each genotype including between two and four variants. With the exception of two viruses, the serotypes of the virus isolates could be predicted by the genotypes. Genotypes 1 and 4 corresponded to serotype 1 isolates, genotype 2 corresponded to serotype 2 isolates, and genotype 3 corresponded to serotype 3 isolates. The single serotype 4 virus mapped to genotype 4. DNA from a virus with a unique serotype could not be amplified with primers that amplified DNA from all other PsHVs, and its classification remains unknown. Viruses representing all four genotypes were found in both the United States and Europe, and it was therefore predicted that serotypes 1, 2, and 3 were present in the United States. Serotype 4 was represented by a single European isolate that could not be genetically distinguished from serotype 1 viruses; therefore, the presence of serotype 4 in the United States could not be predicted. Viruses of genotype 4 were found to be the most commonly associated with Pacheco's disease in macaws and conures and were least likely to be isolated in chicken embryo fibroblasts in the United States. All four genotypes caused deaths in Amazon parrots, but genotype 4 was associated with Pacheco's disease only in Amazons in Europe. Genotypes 2, 3, and 4, but not 1, were found in African grey parrots. Although parrots from the Pacific distribution represent a relatively small percentage of the total number of birds with Pacheco's disease, all four genotypes were found to cause disease in these species.     

Identification of virulence factors in Vibrio cholerae isolated from Iraq during the 2007-2009 outbreak

Thousands of people were infected with Vibrio cholerae during the outbreak in Iraq in 2007-2009. Vibrio cholerae was shown to be variable in its content of virulence determinants and in its antibiotic sensitivity. This study was designed to isolate and characterize clinical and environmental V.?cholerae isolates and to determine antibiotic sensitivity, enzyme and toxin production, and the presence of virulence genes. Eighty clinical and five environmental bacterial isolates were collected and diagnosed by subjecting them to microscopic, biochemical, serological, and molecular analysis. The results revealed that 55% of clinical isolates belonged to the Inaba serotype, 32.5% to the Ogawa serotypes, and 12.5% to the Non-O1 serotype. All environmental V.?cholerae isolates belonged to the Non-O1 serotype. All environmental isolates were sensitive to all examined antimicrobial agents, while all clinical isolates showed a high sensitivity (100%) to ampicillin, gentamicin, cephalothin, tetracycline, erythromycin, and ciprofloxacin, and a high resistance (97.5%) to co-trimoxazole, nalidixic acid, and chloramphenicol. It was found that all V.?cholerae (O1) isolates were resistant to the Vibrio static O129 and all Non-O1 V.?cholerae isolates were sensitive to the Vibrio static O129. All clinical and environmental isolates produced hemolysin (100%) and lecithinase (100%), while they showed various production rates of protease (90% of clinical and 60% of environmental) and lipase (50% of clinical and 20% of environmental). The ompW gene was amplified in all the clinical and environmental V.?cholerae isolates, but not in other related and nonrelated bacteria. Multiplex PCR analysis showed that the toxR gene was amplified in all clinical and environmental isolates, while ctxA, ctxB, tcpA genes were amplified only in clinical (O1) isolates. This study indicates the differences in the production of some enzymes and toxins and in the content of virulence genes between clinical and environmental isolates in Iraq during the outbreak (2007-2009).     

A comparative whole genome analysis of Helicobacter pylori from a human dense South Asian setting

Helicobacter pylori, a Gram-negative bacterium, is associated with a wide range of gastric diseases such as gastritis, duodenal ulcer, and gastric cancer. The prevalence of H pylori and risk of disease vary in different parts of the world based on the prevailing bacterial lineage. Here, we present a contextual and comparative genomics analysis of 20 clinical isolates of H pylori from patients in Bangladesh. Despite a uniform host ethnicity (Bengali), isolates were classified as being part of the HpAsia2 (50%) or HpEurope (50%) population. Out of twenty isolates, eighteen isolates were cagA positive, with two HpEurope isolates being cagA negative, three EPIYA motif patterns (AB, AB-C, and ABC-C) were observed among the cagA-positive isolates. Three vacA genotypes were observed with the s1m1i1dic1 genotype observed in 75% of isolates; the s1m2i1d1c2 and s2m2i2d2c2 genotypes were found to be 15% and 10% of isolates, respectively. The non-virulent genotypes s2m2i2d2c2 was only observed in HpEurope population isolates. Genotypic analysis of oipA gene, present in all isolates, revealed five different patterns of the CT repeat; all HpAsia2 isolates were in “ON” while 20% of HpEurope isolates were genotypically “OFF.” The three blood group antigen binding adhesins encoded genes (bab genes) examined and we observed that the most common genotype was (babA/babB/-) found in eight isolates, notably six were HpAsia2 isolates. The babA gene was found in all HpAsia2 isolates but present in only half of the HpEurope isolates. In silico antibiotic susceptibility analysis revealed that 40% of the strains were multi-drug resistant. Mutations associated with resistance to metronidazole, fluoroquinolone, and clarithromycin were detected 90%, 45%, and 5%, respectively, in H pylori strain. In conclusion, it is evident that two populations of H pylori with similar antibiotic profiles are predominant in Bangladesh, and it appears that genotypically the HpAisa2 isolates are potentially more virulent than the HpEurope isolates.     

Biological and genetic characterisation of Toxoplasma gondii isolates from chickens (Gallus domesticus) from S?o Paulo, Brazil: unexpected findings.

In spite of a wide host range and a world wide distribution, Toxoplasma gondii has a low genetic diversity. Most isolates of T. gondii can be grouped into two to three lineages. Type I strains are considered highly virulent in outbred laboratory mice, and have been isolated predominantly from clinical cases of human toxoplasmosis whereas types II and III strains are considered avirulent for mice. In the present study, 17 of 25 of the T. gondii isolates obtained from asymptomatic chickens from rural areas surrounding S?o Paulo, Brazil were type I. Antibodies to T. gondii were measured in 82 chicken sera by the modified agglutination test using whole formalin-preserved tachyzoites and mercaptoethanol and titres of 1:10 or more were found in 32 chickens. Twenty-two isolates of T. gondii were obtained by bioassay in mice inoculated with brains and hearts of 29 seropositive (> or =1:40) chickens and three isolates were obtained from the faeces of cats fed tissues from 52 chickens with no or low levels (<1:40) of antibodies. In total, 25 isolates of T. gondii were obtained by bioassay of 82 chicken tissues into mice and cats. All type I isolates killed all infected mice within 4 weeks whereas type III isolates were less virulent to mice. There were no type II strains. Tissue cysts were found in mice infected with all 25 isolates and all nine type I isolates produced oocysts. Infected chickens were from localities that were 18-200 km apart, indicating no common source for T. gondii isolates. This is the first report of isolation of predominantly type I strains of T. gondii from a food animal. Epidemiological implications of these findings are discussed.     

Polymorphisms in the beta-tubulin gene of Cryptosporidium parvum differentiate between isolates based on animal host but not geographic origin

Polymerase chain reaction primers were designed to target a region of the Cryptosporidium parvum beta-tubulin gene spanning an intron. Amplification products contained 11 polymorphic positions, representing a sequence divergence of 1.8%, which discriminated between isolates of C. parvum found solely in humans (genotype 1) and those found in humans and animals (genotype 2). Seven of the polymorphic sites were located outside of the intron and the polymorphism between isolates was readily demonstrated by HaeIII restriction digestion. However, all of the sequences from genotype 1 human-derived oocysts isolated in the United States and Australia were conserved. Also, there were no sequence differences between bovine isolates obtained from both continents. Therefore, isolates could not be differentiated based on geographic source of origin.     

Type 1, P and S fimbriae, and afimbrial adhesin I are not essential for uropathogenic Escherichia coli to adhere to and invade bladder epithelial cells

Fimbrial (type 1, P, and S) and afimbrial adhesins, the unique virulence traits of uropathogenic Escherichia coli (UPEC), are well recognized for their role in the initial step of uropathogenesis. In this study, we investigated whether these adhesins are dispensable for UPEC in adherence and invasion of uroepithelial cells by using E. coli isolates (n=40) from cystitis patients and T-24 cells, the bladder carcinoma cell line. We found all isolates adherent to T-24 cells within 15 min of infection. In invasion assay, all isolates could invade T-24 cells to a variable degree; 22.5% of them were found highly invasive. About 33% of isolates that do not have any recognized adhesins were as invasive as other isolates. The amplitude of invasiveness was also independent of the adhesins. In conclusion, this study demonstrates that type 1 fimbriae, P fimbriae, S fimbriae, and afimbrial adhesin I are not required for UPEC to adhere to and invade uroepithelial cells.     

Chemotaxonomic and phylogenetic analyses of Sphingomonas strains isolated from ears of plants in the family Gramineae and a proposal of Sphingomonas roseoflava sp. nov

Chemotaxonomic and phylogenetic characteristics of Sphingomonas strains isolated from plants of the family Gramineae were investigated. All strains contained the monosaccharide (glucuronic acid) type of glycosphingolipid (GSL-1). Most were found also to contain the oligosaccharide-type glycosphingolipids. Fatty acid and sphingosine profiles of the isolates were identical, although the ratio of the contents varies among the isolates. They all contained ubiquinone Q-10, and the G1C contents were from 66 to 68%. Phylogenetic analysis using 16S rRNA gene base sequences revealed that all the isolates were placed in the phylogenetic group of Sphingomonas paucimobilis in the alpha-4 subclass of Proteobacteria. By DNA-DNA hybridization experiments, the plant isolates were divided into five genotypic groups (groups 1 to 5). The strains of group 5 showed common physiological characteristics and formed pink-yellow colored colonies. Based on these results, Sphingomonas roseoflava sp. nov. was proposed for that homology group.     

我国部分地区禽源性大肠杆菌的外膜蛋白型

测定了从我国１８个省、市、自治区分离到的２０４个禽病原性大肠杆菌优势血清型分离株的外膜蛋白型（ＯｕｔｅｒＭｅｍｂｒａｎｅＰｒｏｔｅｉｎＰａｔｅｒｎｓ,ＯＭＰ型）。这些分离株共产生了４个ＯＭＰ型,５６个Ｏ１８分离株可分为３个ＯＭＰ型,５４个Ｏ７８分离株、２８个Ｏ２分离株、２６个Ｏ８８分离株、２２个Ｏ１１分离株和１８个Ｏ２６分离株,分别出现了４、２、１、３和１个ＯＭＰ型。其中,ＯＭＰ１型为６个血清型所共有,ＯＭＰ３型则同时存在于Ｏ１８、Ｏ７８、Ｏ２和Ｏ１１分离株中。结果表明,优势血清型中,Ｏ１８、Ｏ７８、Ｏ２和Ｏ１１分离株具有多样性的ＯＭＰ型,而Ｏ８８、Ｏ２６分离株的ＯＭＰ型则高度一致,所测６个优势血清型的分离株间存在共同的ＯＭＰ型     

Interference of Neisseria gonorrhoeae growth by aerobic bacterial representatives of the urogenital flora

Aerobic bacterial isolates obtained from endocervical, vaginal and urethral swabbings were tested for interference of neisseria gonorrhoeae growth on solid medium. Simultaneous antagonism was studied using the lawn spotting method, and delayed antagonism by the basal spot/lawn method. From 58 swabbings we recuperated a total of 181 isolates, 71 of those were found interfering with at least one out of four gonococcal strains (G-1, G-2, G-3 and G-4). Similar percentages of interfering isolates were obtained from each of the isolation sites. The identification of the interfering isolates has revealed that similar numbers of coagulase negative staphylococci and identical numbers of group D streptococci were found for each of those sites. The majority of the interfering isolates and also of the inhibitory coagulase negative staphylococci showed only simultaneous antagonism. To complete the interference spectrum, we have tested all the active urogenital isolates against four other gonococcal strains (G-7, G-9, G-10 and G-11). This spectrum showed clearly that interference is not an all or none phenomenon. While the gonococcal interference spectrum of most of the Gram positive cocci and the Acinetobacter sp. strains is broad, that of all the other isolates is relatively narrow. Gonococcal strains G-7 and G-9 were the most susceptible to inhibition by the interfering urogenital isolates while strain G-3 was the most resistant one.     

Characterization of Novel Lactobacillus fermentum from Curd Samples of Indigenous Cows from Malnad Region,Karnataka, for their Aflatoxin B1 Binding and Probiotic Properties

Thirty-four isolates of Lactobacillus spp. (LAB) from 34 curd samples were evaluated for their aflatoxin B₁ (AFB₁) binding and probiotic properties. Upon characterization, four LAB isolates (LC3/a, LC4/c, LC/5a, and LM13/b) were found to be effective in removing AFB₁ from culture media with a capacity of above 75%. Staining reaction, biochemical tests, pattern of sugar utilization, and 16s rRNA gene sequence analysis revealed the identity of all the four isolates as L. fermentum. All of them could tolerate acidic pH, salt, and bile, which promise the use of these probiotic bacterial isolates for human applications. These isolates showed poor hydrophobicity and higher auto-aggregation properties. All L. fermentum isolates were found susceptible to gentamycin, chloramphenicol, cefoperazone, ampicillin, and resistant to ciprofloxacin and vancomycin. Results of hemolytic and DNase activity indicated their nonpathogenic nature. Though all L. fermentum isolates found inhibiting the growth of Salmonella ebony, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, maximum inhibition was obtained with isolate LC5/a. Kinetic studies revealed that all four bacteria required a minimum of 2 h to reach stationary phase of AFB₁ binding. AFB₁ binding ability varied from 66 to 85.2% among these four isolates. Bile (0.4%) was significant (P ≤ 0.05) in reducing the AFB₁ binding property of isolates LC3/a, LC4/c, and LM13/b, while increased AFB₁ binding ability was recorded at acidic pH (2.0). AFB₁ binding properties of isolate LC5/a were found least affected by acidic pH and bile. The findings of our study revealed the higher efficiency of L. fermentum isolate LC5/a in reducing the bioavailability of AFB1 in gut, and additionally, it improves the consumers’ health by its various probiotic characters. These beneficial characters, L. fermentum isolates, promise them to use as probiotic formulations alone or in combinations with other beneficial probiotic-bacterial isolates.

     

The role of ISAba1 in expression of OXA carbapenemase genes in Acinetobacter baumannii

ISAba1 was found in all widespread clones of Acinetobacter baumannii in the United Kingdom. All isolates studied had a blaOXA-51-like carbapenemase gene; some also had blaOXA-23-like and/or blaOXA-58-like. Among isolates with blaOXA-51-like as sole carbapenemase gene, only those with ISAba1 adjacent to blaOXA-51-like were carbapenem resistant. Minor differences in blaOXA-51-like sequence were observed in resistant and susceptible isolates. Isolates with blaOXA-23-like in addition were consistently resistant to carbapenems; in all of these ISAba1 lay upstream of blaOXA-23-like, but was not associated with blaOXA-51-like. These results suggest that ISAba1 is providing the promoter for blaOXA-51-like and, probably, for blaOXA-23-like.     

Characterization of mutations in AlHK1 gene from Alternaria longipes: implication of limited function of two-component histidine kinase on conferring dicarboximide resistance

Four series (S, M, R, and W) of Alternaria longipes isolates were obtained based on consecutive induction with Dimethachlon (Dim) and ultraviolet irradiation. These isolates were then characterized according to their tolerance to Dim, sensitivity to osmotic stress, and phenotypic properties. All the induced Dim-resistant isolates showed a higher osmosensitivity than the parental strains, and the last generation was more resistant than the first generation in the M, R, and W series. In addition, the changes in the Dim resistance and osmotic sensitivity were not found to be directly correlated, and no distinct morphologic characteristics were found among the resistant and sensitive isolates, with the exception of the resistant isolate K-11. Thus, to investigate the molecular basis of the fungicide resistance, a group III two-component histidine kinase (HK) gene, AlHK1, was cloned from nineteen A. longipes isolates. AlHK1p was found to be comprised of a six 92- amino-acid repeat domain (AARD), HK domain, and response regulator domain, similar to the Os-1p from Neurospora crassa. A comparison of the nucleotide sequences of the AlHK1 gene from the Dim-sensitive and -resistant isolates revealed that all the resistant isolates contained a single-point mutation in the AARD of AlHK1p, with the exception of isolate K-11, where the AlHK1p contained a deletion of 107 amino acids. Moreover, the AlHK1p mutations in the isolates of each respective series involved the same amino acid substitution at the same site, although the resistance levels differed significantly in each series. Therefore, these findings suggested that a mutation in the AARD of AlHK1p was not the sole factor responsible for A. longipes resistance to dicarboximide fungicides.     

Detection and Comparison of some Ghanaian Isolates of Cacao Swollen Shoot Virus (CSSV) by Enzyme-Linked Immunosorbent Assay (ELISA) and Immunoelectron Microscopy (IEM) Using an Antiserum to CSSV Strain 1A

Various isolates of Cacao Swollen Shoot Virus (CSSV) were detected without difficulty in leaves of Theobroma cacao L. by ELISA and immunosorbent electron microscopy (ISEM) using an antiserum to severe strain 1A. Many isolates were detected with relatively high values at dilutions of 1:30, whereas some other isolates were hardly or not at all detected at this dilution. Strain 1A was detected at dilutions of up to 1: 2560 of crude leaf extracts. All isolates yielding high reactions seem to be serologically closely related to strain 1A. Strains of the mottle-leaf type (AD 191, AD 196, AD 7, AD 36, AD 135, Kpeve) and others were poorly detected; their relationship to strain 1A is discussed. A close correlation was found between results obtained by ELISA and ISEM.     

Electrophoretic patterns of extracellular deoxyribonuclease (DNase) and their correlation with T-type in group A streptococci

Molecular heterogeneity of the extracellular deoxyribonuclease (DNase) in group A streptococci was demonstrated in 42 clinical isolates. Although polyacrylamide gel electrophoretic patterns of the extracellular DNase of all the isolates were heterogeneous, they could be divided into five main patterns with respect to the presence or absence of three DNase components including DNase B. By comparing the electrophoretic patterns of DNase in all the isolates with their T-types, we found that the patterns were quite characteristic for their T-types, especially in the prevalent T-types 12 and 1, and that the isolates of T-types 12 and 1 produced DNase B as their major extracellular DNase. Relative DNase B activity in the total extracellular DNase activity of group A, B, and G isolates was determined by the rapid method of neutralization with anti-DNase B antibody. The results showed neutralization of DNase activity in all the isolates of group A streptococci, largely corresponding to their T-types, but not of the isolates of groups B and G. These results indicate that the electrophoretic patterns of the extracellular DNase of group A streptococci are closely correlated with their T-types, suggesting the physicochemical taxonomic value of these properties.