RESUMO
Among the most economically relevant and environmentally devastating diseases globally are those caused by Phytophthora species. In Australia, production losses in agriculture and forestry result from several well-known cosmopolitan Phytophthora species and infestation of natural ecosystems by Phytophthora cinnamomi have caused irretrievable loss to biodiversity especially in proteaceous dominated heathlands. For this review, all available records of Phytophthora in Australia were collated and curated, resulting in a database of 7 869 records, of which 2 957 have associated molecular data. Australian databases hold records for 99 species, of which 20 are undescribed. Eight species have no records linked to molecular data, and their presence in Australia is considered doubtful. The 99 species reside in 10 of the 12 clades recognised within the complete phylogeny of Phytophthora. The review includes discussion on each of these species' status and additional information provided for another 29 species of concern. The first species reported in Australia in 1900 was Phytophthora infestans. By 2000, 27 species were known, predominantly from agriculture. The significant increase in species reported in the subsequent 20 years has coincided with extensive surveys in natural ecosystems coupled with molecular taxonomy and the recognition of numerous new phylogenetically distinct but morphologically similar species. Routine and targeted surveys within Australian natural ecosystems have resulted in the description of 27 species since 2009. Due to the new species descriptions over the last 20 years, many older records have been reclassified based on molecular identification. The distribution of records is skewed toward regions with considerable activity in high productivity agriculture, horticulture and forestry, and native vegetation at risk from P. cinnamomi. Native and exotic hosts of different Phytophthora species are found throughout the phylogeny; however, species from clades 1, 7 and 8 are more likely to be associated with exotic hosts. One of the most difficult challenges to overcome when establishing a pest status is a lack of reliable data on the current state of a species in any given country or location. The database compiled here for Australia and the information provided for each species overcomes this challenge. This review will aid federal and state governments in risk assessments and trade negotiations by providing a comprehensive resource on the current status of Phytophthora species in Australia. Citation: Burgess TI, Edwards J, Drenth A, et al. 2021. Current status of Phytophthora in Australia. Persoonia 47: 151-177. https://doi.org/10.3767/persoonia.2021.47.05.
RESUMO
Among the most economically relevant and environmentally devastating diseases globally are those caused by Phytophthora species. In Australia, production losses in agriculture and forestry result from several well-known cosmopolitan Phytophthora species and infestation of natural ecosystems by Phytophthora cinnamomi have caused irretrievable loss to biodiversity especially in proteaceous dominated heathlands. For this review, all available records of Phytophthora in Australia were collated and curated, resulting in a database of 7 869 records, of which 2 957 have associated molecular data. Australian databases hold records for 99 species, of which 20 are undescribed. Eight species have no records linked to molecular data, and their presence in Australia is considered doubtful. The 99 species reside in 10 of the 12 clades recognised within the complete phylogeny of Phytophthora. The review includes discussion on each of these species' status and additional information provided for another 29 species of concern. The first species reported in Australia in 1900 was Phytophthora infestans. By 2000, 27 species were known, predominantly from agriculture. The significant increase in species reported in the subsequent 20 years has coincided with extensive surveys in natural ecosystems coupled with molecular taxonomy and the recognition of numerous new phylogenetically distinct but morphologically similar species. Routine and targeted surveys within Australian natural ecosystems have resulted in the description of 27 species since 2009. Due to the new species descriptions over the last 20 years, many older records have been reclassified based on molecular identification. The distribution of records is skewed toward regions with considerable activity in high productivity agriculture, horticulture and forestry, and native vegetation at risk from P. cinnamomi. Native and exotic hosts of different Phytophthora species are found throughout the phylogeny; however, species from clades 1, 7 and 8 are more likely to be associated with exotic hosts. One of the most difficult challenges to overcome when establishing a pest status is a lack of reliable data on the current state of a species in any given country or location. The database compiled here for Australia and the information provided for each species overcomes this challenge. This review will aid federal and state governments in risk assessments and trade negotiations by providing a comprehensive resource on the current status of Phytophthora species in Australia. Citation: Burgess TI, Edwards J, Drenth A, et al. 2021. Current status of Phytophthora in Australia. Persoonia 47: 151-177. https://doi.org/10.3767/persoonia.2021.47.05.
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Objective: To examine the value of serum protein induced by vitamin K absence or antagonist-â ¡ (PIVKA-â ¡) detection in the early diagnosis and surveillance of hepatocellular carcinoma (HCC). Methods: The clinical data of 215 patients with HCC admitted to Department of Hepatobiliary-Pancreatic Surgery of China-Japan Union Hospital of Jilin University from October 2017 to May 2018 were analyzed retrospectively. There were 172 males and 43 females, aged of (59.0±9.3) years old (range 34 to 86 years old). In addition, there were 85 non HCC patients were enrolled in the control group, 42 males and 43 females, aged (54.2±11.3) years old (range 22 to 80 years old). The blood sample of 3 ml was drawn from the elbow vein at 6â¶00 am on the next day of admission, and then was kept in low temperature away from light, and sent for PIVKA-â ¡ detection on the same day. The positive value of AFP was ≥20 µg/L and PIVKA-â ¡ was ≥32 AU/L. The data were analyzed statistically by χ(2) test, t test or rank sum test. The correlation between AFP, PIVKA-â ¡ and tumor maximum diameter was analyzed by linear regression. Results: The sensitivity of PIVKA-â ¡ detection only for the diagnosis of HCC in all stages was significantly higher than AFP or equivalent to AFP, the overall sensitivity of PIVKA-â ¡ and AFP was 85.1% and 52.1%, respectively. But the specificity of PIVKA-â ¡ was lower than that of AFP, they were 78.8% and 96.5%, respectively. In particularly, in the earlier stage of HCC (â a) , the sensitivity of PIVAK-â ¡ to HCC was 64.5%, while the AFP was only 26.3%. Combined detection of PIVKA-â ¡ and AFP significantly improved the diagnostic rate of HCC to 88.4%, and the specificity to 76.5%. Moreover, there was a positive correlation between PIVKA-â ¡ level and the maximum tumor diameter (r(2)=0.587, P<0.05), but there was no correlation between the AFP level and the maximum tumor diameter (r(2)=0.296, P>0.05). The positive rate of PIVKA-â ¡ in the diagnosis of HCC with vascular invasion was also significantly higher than that of AFP (P<0.01) . Conclusions: PIVKA-â ¡ can be used as a serological marker for HCC screening and diagnosis. In particular, PIVKA-â ¡ detection was significantly sensitive than AFP in the earlier stage of HCC. Combined detection of PIVKA-â ¡ and AFP can effectively improve the diagnostic rate of HCC in all stages. The significant elevation of PIVKA-â ¡ is also helpful to determine the tumor aggressiveness, vascular invasion and prognosis of HCC patients.
Assuntos
Biomarcadores/sangue , Carcinoma Hepatocelular , Neoplasias Hepáticas , Precursores de Proteínas/sangue , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/sangue , Carcinoma Hepatocelular/sangue , Carcinoma Hepatocelular/diagnóstico , Detecção Precoce de Câncer , Feminino , Humanos , Neoplasias Hepáticas/sangue , Neoplasias Hepáticas/diagnóstico , Masculino , Pessoa de Meia-Idade , Protrombina , Estudos Retrospectivos , Adulto Jovem , alfa-Fetoproteínas/análiseRESUMO
Cutaneous melanoma (CM) with liver lesions is uncommon in Asia and found in only 14-20% of all cases. Here, we report the case of a 70-year-old male patient with cutaneous melanoma with metastases to the liver. Computerized tomography (CT) revealed multiple hepatic cystic lesions, and hepatic puncture biopsy was used for definitive diagnostics. The primary lesion was found on the patients scalp. We briefly reviewed the literature to summarize the recent progress in diagnosis and treatment of metastatic cutaneous melanoma. Examination of pathology data is still considered the gold standard of diagnosis, while imaging is used to detect metastases, assess the stage of disease and monitor the patients. Metastasectomy, whenever possible, may benefit most patients. Systemic therapies remain the mainstay of the treatment, with some important breakthroughs reported in the recent years. New treatments, such as adult-to-adult living donor liver transplantation, are still in the early stages.
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Neoplasias Hepáticas/secundário , Melanoma/secundário , Neoplasias Cutâneas/patologia , Idoso , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Masculino , Couro Cabeludo/patologia , Neoplasias Cutâneas/secundário , Melanoma Maligno CutâneoAssuntos
Doença Enxerto-Hospedeiro , Transplante de Células-Tronco Hematopoéticas , Hiperlipidemias , Humanos , Criança , Lipoproteína-X , Hiperlipidemias/complicações , População do Leste Asiático , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Fígado , Doença Enxerto-Hospedeiro/etiologiaRESUMO
Liver regeneration after partial hepatectomy (PH) is a complex and well-elaborated biological process whereby synchronized cell proliferation is induced in response to the loss of liver mass. Insulin-like growth factor 1 (IGF1) signaling, which plays a crucial role in normal growth and development, is involved in the process of liver regeneration. To assess the changes in the levels of serum IGF1 and hepatic IGF1 receptor (IGF1R), we established a mouse model for PH. This also allowed us to further explore the mechanisms that participate in the regulation of liver regeneration. Serum IGF1 dramatically decreased immediately after PH, and was mildly elevated afterwards. This was also confirmed in patients who had undergone PH. Immunohistochemistry and Western blotting showed that hepatic IGF1R expression was elevated after surgery in mice. Hepatosomatic index showed a mild elevation 1 week after surgery and a marked elevation after 3 weeks. Western blotting showed increased levels of forkhead box O3 (FOXO3), but the phosphorylated forms of v-akt murine thymoma viral oncogene homolog 1 (AKT1), glycogen synthase kinase 3 beta (GSK3B) and FOXO3 were all downregulated. Our data show that the GSK3B-FOXO3 pathway is activated after PH, and this may be one of the mechanisms that lead to upregulation of hepatic IGF1R after PH. All these changes after surgery promote liver regeneration.
Assuntos
Proteína Forkhead Box O3/metabolismo , Glicogênio Sintase Quinase 3 beta/metabolismo , Hepatectomia , Regeneração Hepática , Fígado/metabolismo , Receptores de Somatomedina/metabolismo , Transdução de Sinais , Regulação para Cima , Animais , Feminino , Humanos , Fígado/cirurgia , Masculino , Camundongos , Camundongos Endogâmicos ICR , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor IGF Tipo 1Assuntos
COVID-19 , Angiografia Coronária/métodos , Oxigenação por Membrana Extracorpórea/métodos , Controle de Infecções , Intervenção Coronária Percutânea/métodos , Infarto do Miocárdio com Supradesnível do Segmento ST , COVID-19/diagnóstico , COVID-19/epidemiologia , COVID-19/prevenção & controle , Cateterismo Cardíaco/métodos , Serviço Hospitalar de Cardiologia/organização & administração , Gestão de Mudança , Comorbidade , Procedimentos Clínicos/organização & administração , Procedimentos Clínicos/tendências , Feminino , Hong Kong/epidemiologia , Humanos , Controle de Infecções/instrumentação , Controle de Infecções/métodos , Controle de Infecções/organização & administração , Masculino , Pessoa de Meia-Idade , SARS-CoV-2/isolamento & purificação , Infarto do Miocárdio com Supradesnível do Segmento ST/diagnóstico , Infarto do Miocárdio com Supradesnível do Segmento ST/epidemiologia , Infarto do Miocárdio com Supradesnível do Segmento ST/cirurgiaRESUMO
BACKGROUND: With the rapid expansion of pet animal populations worldwide, pet-related zoonotic diseases are becoming an important issue in public health. Hong Kong (HK), located in southern China, is one of the most crowded urban centres in the world. The population of pets, especially exotic pets, in HK has grown significantly in recent decades, potentially elevating the risk of pet-related zoonotic diseases. However, no studies have been conducted to explore the knowledge of HK public towards pet-related zoonotic diseases and animal husbandry practices. OBJECTIVES: To evaluate the level of awareness among the HK public of pet-related zoonotic diseases and their understanding of proper animal husbandry practices. METHODS: The study was carried out in HK from June-August 2019 using both online and paper versions of a questionnaire. A total of 362 completed questionnaires (74.3% return rate) were collected and the responses analysed. RESULTS: Sixty percent of the participants were current or past pet owners or planned on becoming pet owners in the coming 2 years, irrespective of their income or size of their living space. Among the participants, pet owners (including those who planned pet ownership) had a relatively higher level of awareness of pet-related zoonotic disease. However, the overall awareness of zoonotic diseases among both pet and non-pet owners was low with a knowledge score of <50%. A similar trend was observed for knowledge about proper animal husbandry practices. CONCLUSIONS: This study showed that the HK public was generally not familiar with pet-related zoonotic diseases and proper pet care. These knowledge gaps could potentially increase the risk of disease transmission. Further studies focusing on specific pet species and on people of different social-economic backgrounds are needed to provide future direction of efforts to reduce the risk of pet-related zoonotic diseases and to enhance pet-related animal and human welfare.
Assuntos
Animais de Estimação , Zoonoses , Criação de Animais Domésticos , Animais , Hong Kong/epidemiologia , Inquéritos e Questionários , Zoonoses/epidemiologiaRESUMO
Seed fungal endophytes play an important beneficial role in the formation of the seedling mycobiome and contribute to plant establishment, but can also occur as latent pathogens and saprotrophs. Current knowledge on the function and diversity of seed fungal endophytes has been gained through studies in agricultural systems whilst knowledge from natural systems is relatively less. We used two co-occurring species from the genus Banksia from four sites in Australia's Sydney Basin Bioregion to investigate the abundance and diversity of seed fungal endophyte communities present in natural ecosystem hosts. Based on results from culturing and DNA sequence analysis of multiple loci, we found that Banksia seeds house a diverse range of fungal endophyte species, that when assigned to functional guilds belonged to multiple trophic modes. Thirty-one of the fungal taxa identified had not been previously reported as endophytes. Amongst the 58 Operational Taxonomic Units identified, Leotiomycetes and Sordariomycetes were the dominant classes and Banksiamyces (Leotiomycetes) and Penicillium (Sordariomycetes) the dominant genera, with many of the species isolated recorded in the literature as having a limited distribution. The two Banksias shared few fungal endophyte species, which were not always present across all study sites. We revealed a 'hidden diversity' within seeds of Banksia from natural ecosystems and provided insights into the influence host species can have on the seed mycobiome.
Assuntos
Ascomicetos , Micobioma , Proteaceae , Micobioma/genética , Ecossistema , DNA Fúngico/genética , Filogenia , Endófitos/genética , Sementes/microbiologia , Ascomicetos/genética , FungosRESUMO
Pulmonary nocardiosis is an uncommon pulmonary infection that is more likely found in immunocompromised patients with underlying chronic lung disease. The presentation of pulmonary nocardiosis is widely variable and shares features with other types of pulmonary infections. Nocardia is also not as easily isolated on standard culture mediums and hence more difficult to identify. We describe the case of a patient with a severe necrotising pneumonia who was chronically immunosuppressed with steroids and has alpha-1 antitrypsin deficiency.
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One of the objectives of metabonomics is to identify subtle changes in metabolite profiles between biological systems of different physiological or pathological states. Gas chromatography mass spectrometry (GC/MS) is a widely used analytical tool for metabolic profiling in various biofluids, such as urine and blood due to its high sensitivity, peak resolution and reproducibility. The availability of the GC/MS electron impact (EI) spectral library further facilitates the identification of diagnostic biomarkers and aids the subsequent mechanistic elucidation of the biological or pathological variations. With the advent of new comprehensive two dimensional GC (GC x GC) coupled to time-of-flight mass spectrometry (TOFMS), it is possible to detect more than 1200 compounds in a single analytical run. In this review, we discuss the applications of GC/MS in the metabolic profiling of urine and blood, and discuss its advances in methodologies and technologies.
Assuntos
Líquidos Corporais/química , Biologia Computacional/métodos , Cromatografia Gasosa-Espectrometria de Massas/métodos , Metabolismo , Plasma/química , Urina/química , Animais , Líquidos Corporais/metabolismo , Cromatografia Gasosa-Espectrometria de Massas/instrumentação , HumanosRESUMO
Antiandrogens such as Casodex (Bicalutamide) are designed to treat advance stage prostate cancer by interfering with androgen receptor-mediated cell survival and by initiating cell death. Treatment of androgen sensitive, non-metastatic LNCaP human prostate cancer cells with 0-100 microM Casodex or 0-10 ng/ml TNF-alpha induces cell death in 20-60% of the cells by 48 h in a dose-dependent manner. In cells treated with TNF-alpha, this is accompanied by the loss of mitochondrial membrane potential (DeltaPsim) and cell adhesion. In contrast, cells treated with Casodex display loss of cell adhesion, but sustained mitochondrial dehydrogenase activity. Overexpression of Bcl-2 in LNCaP cells attenuates the induction of cell death by TNF-alpha but not Casodex, suggesting that mitochondria depolarization is not required for the induction of cell death by Casodex. While both TNF-alpha and Casodex-induced release of cytochrome c in LNCaP cell is predominantely associated with the translocation and cleavage of Bax, our data also suggest that Casodex induces cell death by acting on components downstream of decline of DeltaPsim and upstream of cytochrome c release. Furthermore, while induction of both caspase-3 and caspase-8 activities are observed in TNF-alpha and Casodex-treated cells, a novel cleavage product of procaspase-8 is seen in Casodex-treated cells. Taken together, these data support the hypothesis that Casodex induces cell death by a pathway that is independent of changes in DeltaPsim and Bcl-2 actions and results in an extended lag phase of cell survival that may promote the induction of an invasive phenotype after treatment.
Assuntos
Antagonistas de Androgênios/farmacologia , Carcinoma/tratamento farmacológico , Morte Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias da Próstata/tratamento farmacológico , Antagonistas de Androgênios/uso terapêutico , Anilidas/farmacologia , Carcinoma/metabolismo , Carcinoma/fisiopatologia , Caspases/efeitos dos fármacos , Caspases/metabolismo , Adesão Celular/efeitos dos fármacos , Adesão Celular/fisiologia , Morte Celular/fisiologia , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Sobrevivência Celular/fisiologia , Citocromos c/metabolismo , Humanos , Masculino , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Nitrilas , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/fisiopatologia , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Compostos de Tosil , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/farmacologia , Proteína X Associada a bcl-2RESUMO
This study evaluates the potential of immobilized artificial membrane (IAM) chromatography, in combination with other physicochemical descriptors for high-throughput absorption profiling during lead optimization. An IAM chromatographic method was developed and validated. Absorption profiles of 32 structurally diverse compounds (acidic, basic, neutral and amphoteric) were then evaluated based on their IAM retention factor (log k'IAM), molecular weight (MW), calculated log P (C log P), polar surface area (PSA), hydrogen bonding capacity (HBD and HBA) and calculated Caco-2 permeability (QPCaco). Using regression and stepwise regression analysis, experimental Caco-2 permeability was correlated against log k'IAM and a combination of various physicochemical variables for quantitative structural-permeability relationship (QSPR) study. For the 32 structurally diverse compounds, log k'IAM correlated poorly with Caco-2 permeability values (R2 = 0.227). Stepwise regression analysis confirmed that Clog, PSA, HBD and HBA parameters are not statistically significant and can be eliminated. Correlation between Caco-2 cell uptake and log k'IAM was enhanced when molecular size factor (MW) was included (R2 = 0.555). The exclusion of 11 compounds (paracellularly and actively transported, Pgp substrates and blocker, and molecules with MW lesser than 200 and greater than 800) improved the correlation between Caco-2 permeability, IAM and MW factors to R2 value of 0.84. The results showed that IAM chromatography can only profile the passive absorption of drug molecules. Finally, it was confirmed in this study that the IAM model can accurately identify the Caco-2 permeability of nontransported Pgp substrates, such as verapamil and ketoconazole, through passive permeation because of their high permeability. IAM chromatography, combined with molecular size factor (MW), is useful for elucidating biopartitioning mechanism of drugs.
Assuntos
Permeabilidade da Membrana Celular , Cromatografia Líquida de Alta Pressão/métodos , Membranas Artificiais , Células CACO-2 , Humanos , Ligação de Hidrogênio , Permeabilidade , Espectrofotometria UltravioletaRESUMO
A two-step zero-length cross-linking procedure using active esters was successfully adopted for conjugating metanephrine (MN) and normetanephrine (NM) to bovine serum albumin (BSA). The protein was activated with water-soluble 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in the presence of N-hydroxysulfosuccimide (sulfo-NHS), leading to the formation of active N-succinimidyl esters of some glutamic and aspartic acid carboxyls. The pertinence of this reaction for the coupling of these haptens to carboxylate groups was confirmed via reaction with a model compound, 2-hydroxybenzoic acid, and subsequent characterization using atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used for the quantitative assessment of the hapten/protein ratios of these conjugates. This technique of conjugate characterization demonstrated greater resolution in molecular weight determination compared to nondenaturing polyacrylamide gel electrophoresis (native PAGE). Preliminary results from enzyme-linked immunosorbent assay (ELISA) and inhibition ELISA procedures using test antisera confirmed that the synthesized immunogens were highly antigenic and elicited specific antibody responses in BALB/c mice against the haptens.
Assuntos
Anticorpos/sangue , Metanefrina/imunologia , Normetanefrina/imunologia , Grupos de População Animal , Animais , Antígenos/química , Antígenos/imunologia , Ligação Competitiva , Reagentes de Ligações Cruzadas/química , Ensaio de Imunoadsorção Enzimática , Etildimetilaminopropil Carbodi-Imida/química , Feminino , Glutaral/química , Haptenos/imunologia , Metanefrina/química , Camundongos , Camundongos Endogâmicos BALB C , Normetanefrina/química , Ácido Salicílico/química , Soroalbumina Bovina/química , Soroalbumina Bovina/imunologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Succinimidas/químicaRESUMO
A survey of the endophytic fungi in fronds of Livistona chinensis was carried out in Hong Kong. The endophyte assemblages identified using morphological characters consisted of 16 named species and 19 'morphospecies', the latter grouped based on cultural morphology and growth rates. Arrangement of taxa into morphospecies does not reflect species phylogeny, and therefore selected morphospecies were further identified based on ribosomal DNA (rDNA) sequence analysis. The 5.8S gene and flanking internal transcribed spacers (ITS1 and ITS2) regions of rDNA from 19 representative morphospecies were amplified by the polymerase chain reaction and sequenced. Phylogenetic analysis based on 5.8S gene sequences showed that these morphospecies were filamentous Ascomycota, belonging in the Loculoascomycetes and Pyrenomycetes. Further identification was conducted by means of sequence comparison and phylogenetic analysis of both the ITS and 5.8S regions. Results showed that MS704 belonged to the genus Diaporthe and its anamorph Phomopsis of the Valsaceae. MS594 was inferred to be Mycosphaerella and its anamorph Cladosporium of the Mycosphaerellaceae. MS339, MS366, MS370, MS395, MS1033, MS1083 and MS1092 were placed in the genus Xylaria of the Xylariaceae. MS194, MS375 and MS1028 were close to the Clypeosphaeriaceae. MS191 and MS316 were closely related to the Pleosporaceae within the Dothideales. The other 5 morphospecies, MS786, MS1043, MS1065, MS1076 and MS1095, probably belong in the Xylariales. The value of using DNA sequence analysis in the identification of endophytes is discussed.
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ABSTRACT Phytophthora infestans isolates collected from potato and tomato crops from various parts of Nepal during the 1999 and 2000 crop seasons were characterized for nuclear and mitochondrial DNA polymorphisms using restriction fragment length polymorphism markers. The nuclear DNA probe RG57 detected 11 multilocus genotypes among 280 isolates. Three genotypes were detected 21 times or more, constituting 94% of the total population, whereas frequencies of other genotypes ranged from 0.004 to 0.014. The overall genotypic diversity as estimated by the Gleason index was 1.78. Most of the overall diversity was present at the highest level (i.e., interregional, 46%), indicating limited gene flow among regions. Cluster analysis of multilocus genotypes derived from RG57 and mating type data for Nepalese isolates and representative isolates worldwide showed Nepalese isolates grouping into four clusters. Characterization of 67 isolates for mitochondrial DNA polymorphisms revealed the presence of two mt-haplotypes, Ia and Ib with the proportions of 0.88 and 0.12, respectively. Polymorphisms in nuclear and mitochondrial DNA revealed a moderate level of diversity in this population. Genotype NP3 had an identical RG57 fingerprint to US1 and had mt-haplotype Ib, confirming the presence of an old population in Nepal. Most of the genotypes had a different RG57 fingerprint than that of US1 and mt-haplotype Ia, the common characteristics of new populations. The presence of a new population at high proportions in Nepal was consistent with the global trend of mt-haplotype distribution, and suggests the displacement of old populations. This study indicates at least three possible introductions of P. infestans to Nepal.
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Twenty-one Rhizoctonia-like fungal strains were isolated from the roots of four terrestrial orchid species from various locations in Hong Kong. The cultural morphology, nuclear number of the hyphal cell, pore ultrastructure, and RAPD and CAPS analyses of rDNA fragments revealed that most of these isolates were associated with the genera Ceratorhiza and Epulorhiza. RAPD analysis showed the presence of genetic diversity between the isolates from different hosts and locations. The compatibility between a selection of these Ceratorhiza and Epulorhiza isolates and 14 orchid species was determined using a symbiotic germination method. The germination and development of three orchid species, Arundina chinensis, Spathoglottis pubescens, and Spiranthes hongkongensis, were strongly stimulated by the Epulorhiza isolates. Habenaria dentata was found to form symbionts successfully with a Ceratorhiza isolate.
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A new taxon with Dyrithium-like characteristics was collected from Lake Fuxian in China. The taxon is typical of the Amphisphaeriaceae in that it has relatively large, ostiolate, immersed ascomata, unitunicate asci with a J+ subapical ring, and brown ascospores. It is similar to Dyrithium in that it has muriform ascospores, but considerable confusion surrounds this genus. In Dyrithium asci are bitunicate and lack a J+ subapical ring, while this was not true of our species. A new genus, Dyrithiopsis, therefore is established to accommodate this new taxon. Details of its anamorph also are provided, based on cultural studies. Parsimony analyses of part of the large-subunit rDNA provide further evidence to support the familial placement of this new genus in the Amphisphaeriaceae. The taxonomic position of Dyrithium also is discussed.