Presence of a novel 16S-23S rRNA gene intergenic spacer insert in Bradyrhizobium canariense strains

Seven slow-growing bacterial strains isolated from root nodules of yellow serradella (Ornithopus compressus) that originated from Asinara Island on North Western Sardinia in Italy were characterized by partial 16S rRNA gene and intergenic spacer (ITS) sequencing as well as amplified fragment length polymorphism (AFLP) genomic fingerprinting. The results indicated that the O. compressus isolates belong to the Bradyrhizobium canariense species. The analysis of ITS sequences divided the branch of B. canariense strains into two statistically separated groups (ITS clusters I and II). All the strains in ITS cluster I showed the presence of unique oligonucleotide insert TTAGAGACTTAGGTTTCTK. This insert was neither found in other described species of the family Rhizobiaceae nor in any other bacterial families and can be used as a natural and high selective genetic marker for ITS cluster I of B. canariense strains. ITS grouping of O. compressus isolates was supported by the unweighted pair group method with arithmetic averages cluster analysis of their AFLP patterns, suggesting that the strains of ITS cluster II were genetically closer to each other than to isolates from the ITS cluster I. A taxonomic importance is supposed of the revealed 19 bp ITS insert for an intraspecific division within high heterogeneous B. canariense species.     

Species delimitation in the African Armillaria complex by analysis of the ribosomal DNA spacers

Thirteen Armillaria isolates, collected from various geographical areas in tropical Africa and previously characterized by cultural morphology, pairing tests and isozyme analysis, were evaluated using the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). DNA regions corresponding to the intergenic spacer (IGS) and internal transcribed spacer (ITS) were amplified and analyzed by restriction enzyme digestion. The IGS amplification products were about 875 bp long and uniform in length among the isolates. The amplified-ITS region showed two different lengths corresponding to two groups. The first group included the isolates believed to belong to A. mellea ssp. africana and two Kenyan isolates (K11 and K12) belonging to a yet unnamed biological species. The second group included isolates identified as A. heimii and a Tanzanian isolate (T7). Each length variant of the ITS showed distinct RFLP banding patterns. Digestion with EcoRI confirmed the two polymorphic groups while the endonucleases AluI and NdeII discriminated the A. mellea isolates from the Kenyan isolates K11 and K12. In addition, the latter enzyme showed a slight dissimilarity between the A. heimii isolates from Western and Eastern Africa (C1 and Z1). Digestion with HinfI cleaved the isolates of A. heimii into two sub-groups corresponding to the heterothallic and homothallic forms. This endonuclease also indicated that the isolate T7, originating from Tanzania, was clearly similar to the heterothallic species A. heimii. Data presented support the maintenance of three distinct species of Armillaria in tropical Africa with A. heimii as a variable species, the isolates of which were separated in accordance with their sexual system. The results indicate that PCR-RFLP can be used as a simple and speedy taxonomical tool for the ecological studies of Armillaria species.     

Analysis of the 5.8S rRNA gene and the internal transcribed spacers in Naegleria spp. and in N. fowleri

Internal transcribed spacers (ITS) and the 5.8S ribosomal gene of 21 Naegleria fowleri strains and eight other species including Naegleria gruberi were sequenced. The results showed that this region can help differentiate between and within species. The phylogeny of Naegleria spp. deduced from the ITS and the 5.8S gene produced four major lineages, fowleri-lovaniensis, galeacystis-italica-clarki-gruberi-australiensis, andersoni-jamiesoni, and pussardi, that fit perfectly with those inferred from the 18S rRNA gene analysis. The N. gruberi isolate, NG260, was closely related to Naegleria pussardi. The other N. gruberi isolates branched together with Naegleria australiensis in another lineage. The ITS and 5.8S results for N. fowleri were congruent with those previously deduced by RAPD analysis. The phylogenetic analysis inferred from ITS and RAPD data revealed two major groups. The French Cattenom and Chooz and South Pacific strains constituted the first group. The second group encompassed the strains corresponding to the Euro-American and Widespread RAPD variants and shared the same substitution in the 5.8S gene. In addition, it was possible to define species specific primers in ITS regions to rapidly identify N. fowleri.     

Oogonial biometry and phylogenetic analyses of the Pythium vexans species group from woody agricultural hosts in South Africa reveal distinct groups within this taxon

Pythium vexans fits into the internal transcribed spacer (ITS) clade K sensu Lévesque & De Cock (2004). Within clade K, P. vexans forms a distinct clade containing two enigmatic species, Pythium indigoferae and Pythium cucurbitacearum of which no ex-type strains are available. In South Africa, as well as in other regions of the world, P. vexans isolates are known to be heterogeneous in their ITS sequences and may consist of more than one species. This study aimed to investigate the diversity of South African P. vexans isolates, mainly from grapevines, but also citrus and apple using (i) phylogenetic analyses of the ITS, cytochrome c oxidase (cox) I, cox II, and β-tubulin regions and (ii) seven biometric oogonial parameters. Each of the phylogenies clustered P. vexans isolates into a single well-supported clade, distinct from other clade K species. The β-tubulin region was phylogenetically uninformative regarding the P. vexans group. The ITS phylogeny and combined cox I and II phylogenies, although each revealing several P. vexans subclades, were incongruent. One of the most striking incongruences was the presence of one cox subclade that contained two distinct ITS subclades (Ib and IV). Three groups (A-C) were subjectively identified among South African P. vexans isolates using (i) phylogenetic clades (ITS and cox), (ii) univariate analysis of oogonial diameters, and (iii) multivariate analyses of biometric oogonial parameters. Group A is considered to be P. vexans s. str. since it contained the P. vexans CBS reference strain from Van der Plaats-Niterink (1981). This group had significantly smaller oogonial diameters than group B and C isolates. Group B contained the isolates from ITS subclades Ib and IV, which formed a single cox subclade. The ITS subclade IV isolates were all sexually sterile or produced mainly abortive oospores, as opposed to the sexually fertile subclade Ib isolates, and may thus represent a distinct assemblage within group B. Although ITS subclade Ib included the P. indigoferae ex-type sequence, this group was considered to be P. vexans since South African isolates in this clade produced globose sporangia. Group C contained four apple isolates that were related to, but distinct from P. cucurbitacearum. Although P. vexans groups A-C might be distinct species, they are not described here as such due to (i) these groups only representing some of the known diversity in P. vexans, (ii) conflicting gene tree phylogenies preventing phylogenetic species identification, and (iii) sexually sterile isolates preventing the broad application of biometrical data.     

Intraspecific and within-isolate sequence variation in the ITS rRNA gene region of Pythium mercuriale sp. nov. (Pythiaceae)

Sixteen Pythium isolates from diverse hosts and locations, which showed similarities in their morphology and sequences of the internal transcribed spacer (ITS) region of their rRNA gene, were investigated. As opposed to the generally accepted view, within single isolates ITS sequence variations were consistently found mostly as part of a tract of identical bases (A-T) within ITS1, and of GT or GTTT repeats within the ITS2 sequence. Thirty-one different ITS sequences obtained from 39 cloned ITS products from the 16 isolates showed high sequence and length polymorphisms within and between isolates. However, in a phylogenetic analysis, they formed a cluster distinct from those of other Pythium species. Additional sequencing of two nuclear genes (elongation factor 1 alpha and beta-tubulin) and one mitochondrial gene (nadh1) revealed high levels of heterozygosity as well as polymorphism within and between isolates, with some isolates possessing two or more alleles for each of the nuclear genes. In contrast to the observed variation in the ITS and other gene areas, all isolates were phenotypically similar. Pythium mercuriale sp. nov. (Pythiaceae) is characterized by forming thin-walled chlamydospores, subglobose to obovoid, papillate sporangia proliferating internally and smooth-walled oogonia surrounded by multiple antheridia. Maximum likelihood phylogenetic analyses based on both ITS and beta-tubulin sequence data place P. mercuriale in a clade between Pythium and Phytophthora.     

Restriction analysis of the amplified ribosomal DNA spacers ITS1 and ITS2 of <Emphasis Type="Italic">Bipolaris sorokiniana</Emphasis> isolates

The purpose of this study was to examine the genotypic variability of Bipolaris sorokiniana by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis using rDNA. Fifty B. sorokiniana isolates from Brazil and other countries, one Bipolaris oryzae and six Drechslera teres isolates were used. The intragenic spacer regions (ITS1 and ITS2) were the regions used for characterization of isolates. The amplification products for both ITS regions, showed two DNA fragments for all isolates. Two B. sorokiniana isolates presented an intraspecific variability showing a third fragment for the ITS1 region. The dendrograms generated with PCR-RFLP data showed intra- and inter-specific groups. The dendrograms showed that most of Brazilian isolates clustered together forming groups between them, and this behavior was repeated with most isolates from other countries. The dendrograms did not enable the separation of B. sorokiniana isolates by their geographic origin or host type. These results suggest the occurrence of gene flow between different populations of the fungus isolated in geographically distant regions and lends cogency to the occurrence of gene flow between species.     

Genetic Diversity of Ostreopsis ovata (Dinophyceae) from Malaysia

The genus Ostreopsis is an important component of benthic and epiphytic dinoflagellate assemblages in coral reefs and seaweed beds of Malaysia. Members of the species may produce toxins that contribute to ciguatera fish poisoning. In this study, two species have been isolated and cultured, Ostreopsis ovata and Ostreopsis lenticularis. Analyses of the 5.8S subunit and internal transcribed spacer regions ITS1 and ITS2 of the ribosomal RNA gene sequences of these two species showed that they are separate species, consistent with morphological designations. The nucleotide sequences of the 5.8S subunit and ITS1 and ITS2 regions of the rRNA gene were also used to evaluate the interpopulation and intrapopulation genetic diversity of O. ovata found in Malaysian waters. Results showed a low level of sequence divergence within populations. At the interpopulation level, the rRNA gene sequence distinguished two groups of genetically distinct strains, representative of a Malacca Straits group (isolates from Port Dickson) and a South China Sea group (isolates from Pulau Redang and Kota Kinabalu). Part of the sequences in the ITS regions may be useful in the design of oligonucleotide probes specific for each group. Results from this study show that the ITS regions can be used as genetic markers for taxonomic, biogeographic, and fine-scale population studies of this species. Received September 15, 2000; accepted December 15, 2000     

Intraspecies Analysis: Comparison of ITS Sequence Data and Gene Intron Sequence Data with Breeding Data for a Worldwide Collection of Gonium pectorale

The morphologically uniform species Gonium pectorale is a colonial green flagellate of worldwide distribution. The affinities of 25 isolates from 18 sites on five continents were assessed by both DNA sequence comparisons and sexual compatibility. Complete sequences were obtained (i) for the internal transcribed spacer ITS-1 and ITS-2 regions of ribosomal DNA and (ii) for each of three single-copy spliceosomal introns, two in a small G protein and one in the actin gene. ITS sequences appeared to homogenize sufficiently rapidly to behave as a single copy gene. Intron sequence differences between isolates in this species reached nucleotide substitution saturation, while ITS sequences did not. Parsimony and evolutionary distance analysis of the two types of DNA data gave essentially the same tree conformation. By all these criteria, the group of G. pectorale isolates fell into two main clades, A and B. Clade A, with isolates from four continents, was comprised of four subclades of quite closely related isolates, plus one strain of ambiguous affinity. Clade B was comprised of two subclades represented by South African and South American isolates, respectively; thus, only subclades of clade B showed geographical localization. With respect to mating, all isolates except one homothallic strain and one apparently sterile strain fell into either one or the other of two mating types. Pairings in all possible combinations revealed that isolates from the same site formed abundant zygotes, which germinated to produce new, sexually active organisms. Zygotes were also formed in many pairings of other combinations, including crosses of clade A with clade B organisms, but none of the latter produced viable germlings. The ability to mate and produce viable progeny that were themselves capable of sexual reproduction was restricted to members of subclades established on the basis of DNA sequence similarities. Thus, the grades of difference in both nuclear intron sequences and rDNA ITS sequences paralleled those observed in the sexual analysis. Received: 9 March 1998 / Accepted: 1 June 1998     

Differentiation of two ovine Babesia based on the ribosomal DNA internal transcribed spacer (ITS) sequences

The first and second internal transcribed spacers (ITS1, ITS2) as well as the intervening 5.8S coding region of the rRNA gene for six Babesia spp. isolated from different geographic origins were characterized. Varying degrees of ITS1 and ITS2 intra- and inter-species sequence polymorphism were found among these isolates. Phylogenetic analysis of the ITS1-5.8S gene-ITS2 region clearly separated the isolates into two clusters. One held an unidentified Babesia sp. transmitted by Hyalomma anatolicum anatolicum. The second held five other isolates, which were considered to be Babesia motasi. Each Babesia species cluster possessed ITS1 and ITS2 of unique size(s) and species specific nucleotide sequences. The results showed that ITS1, ITS2 and the complete ITS1-5.8S-ITS2 region could be used to discriminate these ovine Babesia spp. effectively.     

Electrophoretic analysis of ITS from Piscirickettsia salmonis Chilean isolates

Piscirickettsia salmonis is the most important pathogen in salmonid mariculture in Chile. Since it was reported numerous piscirickettsiosis outbreaks have occurred differing in virulence and mortality. Genetic variability of P. salmonis isolates has been suggested as one factor to explain this. However until now isolates obtained from outbreaks have not been analyzed. Knowledge of genetic variability of P. salmonis is very limited and also a useful screening method for genetic variations in isolates without sequencing is not available. Here we report an electrophoretic analysis of internal transcribed spacer region (ITS) of eleven P. salmonis isolates obtained from different salmon species and places in southern Chile. When PCR products were submitted to polyacrylamide gel electrophoresis (PAGE) a characteristic electrophoretic pattern was observed, distinguishable from ITS of other bacteria, including fish pathogens. Even though this pattern is conserved in all isolates, a difference in ITS electrophoretic mobility was observed, determining clearly two groups: ITS with higher or with lower electrophoretic mobility, including LF-89 and EM-90 isolates, respectively. A higher ITS sequence homology inside each group was shown by heteroduplex mobility assay (HMA). Our results show that genetic variability between Chilean P. salmonis isolates allows the differentiation of two groups with similar behavior observed previously when six P. salmonis isolates from three geographic origins were analyzed by 16S, 23S and ITS sequencing. PAGE analysis of ITS and HMA could be a basis to develop an assay for screening genetic variability between P. salmonis isolates.     

链格孢属小孢子种的RAPD分析*

用筛选出的12个随机引物,对链格孢属Alternaria13个小孢子种和作为对照的3个大孢子种共55个分离系(isolates)进行RAPD分析。大孢子种Alternariasolani、A.porri和形态独特的A.leucanthemi在树状聚类图上遗传距离0.44处与所有供试小孢子种区分开,它们彼此之间在遗传距离0.25处相区分,表明所采用的RAPD分析方法适于链格孢种间亲缘关系的研究。所有供试的链格孢小孢子种在遗传距离0.31水平上被聚在一起,表明它们之间的亲缘关系较近。A.infectoria与其它链格孢小孢子种之间遗传距离较远;A.longipes的3个分离系和A.brassicicola的7个分离系在较低的遗传距离上被聚在一起,表明它们是独立的种。其它供试链格孢小孢子种的不同分离系在树状聚类图上未显示明确区分。     

Phylogenetic analysis of Aspergillus section Circumdati based on sequences of the internal transcribed spacer regions and the 5.8 S rRNA gene

Phenotypic features and sequences of the internal transcribed spacer (ITS) regions and the 5.8 S rRNA gene of type or neotype strains and other isolates of the 17 species currently assigned to Aspergillus section Circumdati and some potentially related species were analyzed. Parsimony analysis of sequence data indicated that Aspergillus section Circumdati is paraphyletic. Aspergillus campestris, A. lanosus, and A. dimorphicus with A. sepultus were found to be more closely related to Aspergillus sections Candidi, Flavi, and Cremei, respectively. These results were also supported by phenotypic data. A. robustus and A. ochraceoroseus were found not to be related to any of the species examined. Species of the proposed revised Aspergillus section Circumdati formed two main clades, which could also be distinguished based on phenotypic methods. Phylogenetic analysis of sequence data of other isolates assigned to species of the revised section indicates that either some of these isolates were misidentified or species concepts of A. ochraceus, A. melleus, and A. petrakii should be reconsidered.     

rDNA-RFLP identification of Candida species in immunocompromised and seriously diseased patients

PCR was used to amplify a targeted region of the ribosomal DNA of 76 Candida spp. isolates from immunocompromised and seriously diseased patients. Thirty-seven strains isolated from different anatomical sites of 11 patients infected with HIV (Vitória, ES, Brazil), 26 isolates from patients under treatment at Odilon Behrens Hospital and 13 isolates from skin and urine samples from S?o Marcos Clinical Analysis Laboratory (Belo Horizonte, Brazil) were scored. Fragments of rDNA were amplified using primer pairs ITS1-ITS4, for the amplification of ITS1 and ITS2 regions, including the gene for the 5.8 s subunit. Amplification resulted in fragments ranging in size from 350 to 950 bp. Amplicons were digested with eight restriction enzymes. A pattern of species-specificity among the different medically important Candida species could be identified following restriction digestion of the PCR products. Candida albicans was the species most frequently observed, except for the group of newborns under treatment at the Odilon Behrens Hospital and for the isolates from the clinical analysis laboratory. C. parapsilosis was the species most frequently observed in these two groups.     

Cylindrocladium buxicola, a new species affecting Buxus spp., and its phylogenetic status

A leaf and twig blight disease of Buxus spp. was found to be associated with a new species of Cylindrocladium. The novel species status was confirmed using morphological characters, sequencing of the ribosomal 5.8S RNA gene and the flanking internal transcribed spacers (ITS), the β-tubulin gene, and the high mobility group (HMG) of the MAT2 mating type gene. Cylindrocladium buxicola is proposed as a new name. Fifteen isolates from the UK and one isolate from New Zealand were paired in all combinations but no fertile perithecia were obtained suggesting that C. buxicola is heterothallic and all isolates belonged to one mating type. AFLP analysis showed that the isolates collected in the UK and New Zealand are genetically homogenous. Phylogenetic analyses indicated that this species falls within a new lineage.     

Analysis of the Genetic Structure of Sclerotinia sclerotiorum (Lib.) de Bary Populations from Different Regions and Host Plants by Random Amplified Polymorphic DNA Markers

The genetic diversity and genetic structure of a population of isolates of Sclerotinia sclerotiorum (Lib.) de Bary from different regions and host plants were investigated using the random amplified polymorphic DNA (RAPD) method with 20 random decamer primer pairs in order to provide some information on the phylogenetic taxa and breeding for resistance to sclerotinia stem rot. A minimum of three and a maximum of 15 unambiguously amplified bands were generated, furnishing a total of 170 bands ranging in size from 100to 3 200 bp, corresponding to an average of 8.5 bands per primer pair. One hundred and four of these 170bands (61.2%) were polymorphic, the percentage of polymorphic bands for each primer pair ranging from 0.0% to 86.7%. The genetic relationships among the isolates, based on the results of RAPD analysis, were examined. The genetic similarity of all selected isolates was quite high. At the species level, the genetic diversity estimated by Nei's gene diversity (h) was 0.197 and S hannon's index of diversity (I) was 0.300. The unweighted pair-group mean analysis (UPGMA) cluster analysis showed that most isolates from the same regions were grouped in the same cluster or a close cluster. The population of isolates from Hefei (Anhui Province, China) was more uniform and relatively distant to other populations. The Canadian population collected from carrot (Daucus carota var. sativa DC.) was relatively close to the Polish population collected from oilseed rape (Brassica napus L.) plants. There was no relationship between isolates from the same host plants. An analysis of molecular variance (AMOVA) revealed that the percentage of variance attributable to variation among and within populations was 50.62% and 49.38%, respectively. When accessions from China, Europe, and Canada were treated as three separate groups, the variance components among groups,among populations within groups, and within populations were -0.96%, 51.48%, and 49.47%, respectively.The genetic differentiations among and within populations were highly significant (P ＜ 0.001). Similarly, the coefficient of gene differentiation (Gst) in total populations calculated by population genetic analysis was 0.229 4, which indicated that the genetic variation among populations was 22.94%. The gene flow (Nm)was 1.68, which indicated that the gene permutation and interaction among populations was relatively high.     

Extent of horizontal gene transfer in evolution of Streptococci of the salivarius group

The phylogenetically closely related species Streptococcus salivarius and Streptococcus vestibularis are oral bacteria that are considered commensals, although they can also be found in human infections. The relationship between these two species and the relationship between strains isolated from carriers and strains responsible for invasive infections were investigated by multilocus sequence typing and additional sequence analysis. The clustering of several S. vestibularis alleles and the extent of genomic divergence at certain loci support the conclusion that S. salivarius and S. vestibularis are separate species. The level of sequence diversity in S. salivarius alleles is generally high, whereas that in S. vestibularis alleles is low at certain loci, indicating that the latter species might have evolved recently. Cluster analysis indicated that there has been genetic exchange between S. salivarius and S. vestibularis at three of the nine loci investigated. Horizontal gene transfer between streptococci belonging to the S. salivarius group and other oral streptococci was also detected at several loci. A high level of recombination in S. salivarius was revealed by allele index association and split decomposition sequence analyses. Commensal and infection-associated S. salivarius strains could not be distinguished by cluster analysis, suggesting that the pathogen isolates are opportunistic. Taken together, our results indicate that there is a high level of gene exchange that contributes to the evolution of two streptococcal species from the human oral cavity.     

Floral and vegetative morphometrics of five Pleurothallis (Orchidaceae) species: correlation with taxonomy,phylogeny, genetic variability and pollination systems

Morphometric analyses of vegetative and floral characters were conducted in 21 populations of five Pleurothallis (Orchidaceae) species occurring in Brazilian 'campo rupestre' vegetation. A phylogenetic analysis of this species group was also carried out using nuclear ribosomal DNA internal transcribed spacers (ITS1 and ITS2). Results of the ordination and cluster analyses agree with species' delimitation revealed by taxonomic and allozyme studies. The groups formed in ordination analysis correspond to the pollinator groups determined in a previous pollination study. Relationships among the species in the cluster analysis using only vegetative characters are similar to those found in a previous allozyme study, but those indicated by cluster analysis using only floral characters differ. These results support the hypothesis that floral similarities are due to convergence driven by similar pollination mechanisms, and therefore floral traits may not be good indicators of phylogenetic relationships in this group. The results of the phylogenetic analysis support this conclusion to some extent. There is no correlation between genetic (allozyme) and morphological variability in the populations nor in the way this variability is distributed among conspecific populations. We describe a new subspecies of Pleurothallis ochreata based on differences in vegetative and chemical characters as well as geographic distribution. Absence of differentiation in floral characters, attraction of the same pollinator species, interfertility and genetic similarity support the argument for subspecific rather than specific status.     

Combined molecular and biochemical approach identifies Aspergillus japonicus and Aspergillus aculeatus as two species

We examined nine Aspergillus japonicus isolates and 10 Aspergillus aculeatus isolates by using molecular and biochemical markers, including DNA sequences of the ITS1-5.8S rRNA gene-ITS2 region, restriction fragment length polymorphisms (RFLP), and secondary-metabolite profiles. The DNA sequence of the internal transcribed spacers (ITS1 and ITS2) and the 5.8S rRNA gene could not be used to distinguish between A. japonicus and A. aculeatus but did show that these two taxa are more closely related to each other than to other species of black aspergilli. Aspergillus niger pyruvate kinase (pkiA) and pectin lyase A (pelA) and Agaricus bisporus 28S rRNA genes, which were used as probes in the RFLP analysis, revealed clear polymorphism between these two taxa. The A. niger pkiA and pelA probes placed six strains in an A. japonicus group and 12 isolates in an A. aculeatus group, which exhibited intraspecific variation when they were probed with the pelA gene. The secondary-metabolite profiles supported division of the isolates into the two species and differed from those of other black aspergilli. The strains classified as A. japonicus produced indole alkaloids and a polar metabolite, while the A. aculeatus isolates produced neoxaline, okaramins, paraherquamidelike compounds, and secalonic acid. A. aculeatus CBS 114.80 showed specific RFLP patterns for all loci examined. The secondary-metabolite profile of strain CBS 114.80 also differed from those of A. japonicus and A. aculeatus. Therefore, this strain probably represents a third taxon. This study provides unambiguous criteria for establishing the taxonomic positions of isolates of black aspergilli, which are important in relation to industrial use and legal protection of these organisms.     

金耳与其近似种的rDNA-ITS序列分析

对金耳(Tremella aurantialba)的担子果、酵母状分生孢子培养物和菌丝培养物的核糖体DNA内部转录间隔区(ITS)序列进行PCR扩增和测序。结果表明金耳担子果的ITS区PCR产物均为碱基数不同的两条带,片段长度和序列与酵母状分生孢子培养物、菌丝培养物一致。通过对ITS1和ITS2联合进行系统发育分析表明金耳酵母状分生孢子培养物归属于银耳属的金耳,参与组成担子果的寄主菌丝为毛韧革菌(Stereum hirsutum)。结合GenBank中登录的金黄银耳、脑状银耳、橙黄银耳等近似种构建了的系统发育树,结果支持形态学证据,表明金耳是一个独立种。     

Allozyme analysis of Trichinella isolates from various host species and geographical regions.

Allozyme analysis was carried out on 152 Trichinella isolates from synanthropic and wild animals and from humans; the isolates were collected from 5 continents. The analysis, involving 27 enzymes, revealed the presence of 8 distinct gene pools, termed T1-T8. Four of the genetic groups represent the 4 previously proposed species: Trichinella spiralis sensu stricto (T1), Trichinella nativa (T2), Trichinella nelsoni (T7), and Trichinella pseudospiralis (T4). The other 4, T3, T5, T6, and T8 are distinct from previously described species. The absence of allozymic hybrid patterns among even sympatric groups indicates a lack of gene flow among the groups. Principal component analysis and the unweighted pair group method of analysis were used to assemble allozyme patterns of the 152 isolates into discrete groups and to show their relative relationships. Both analyses indicated the presence of 8 primary clusters that correlated with the gene pools revealed by direct allozyme profile analysis. The absence of evidence of gene flow among the gene pools and the high level of allozymic differentiation between the cluster groups support the concept that the genus Trichinella is composed of several sibling species.