Elevated Atmospheric Carbon Dioxide Concentrations Amplify Alternaria alternata Sporulation and Total Antigen Production

Background

Although the effect of elevated carbon dioxide (CO₂) concentration on pollen production has been established in some plant species, impacts on fungal sporulation and antigen production have not been elucidated.

Objective

Our purpose was to examine the effects of rising atmospheric CO₂ concentrations on the quantity and quality of fungal spores produced on timothy (Phleum pratense) leaves.

Methods

Timothy plants were grown at four CO₂ concentrations (300, 400, 500, and 600 μmol/mol). Leaves were used as growth substrate for Alternaria alternata and Cladosporium phlei. The spore abundance produced by both fungi, as well as the size (microscopy) and antigenic protein content (ELISA) of A. alternata, were quantified.

Results

Leaf carbon-to-nitrogen ratio was greater at 500 and 600 μmol/mol, and leaf biomass was greater at 600 μmol/mol than at the lower CO₂ concentrations. Leaf carbon-to-nitrogen ratio was positively correlated with A. alternata spore production per gram of leaf but negatively correlated with antigenic protein content per spore. At 500 and 600 μmol/mol CO₂ concentrations, A. alternata produced nearly three times the number of spores and more than twice the total antigenic protein per plant than at lower concentrations. C. phlei spore production was positively correlated with leaf carbon-to-nitrogen ratio, but overall spore production was much lower than in A. alternata, and total per-plant production did not vary among CO₂ concentrations.

Conclusions

Elevated CO₂ concentrations often increase plant leaf biomass and carbon-to-nitrogen ratio. Here we demonstrate for the first time that these leaf changes are associated with increased spore production by A. alternata, a ubiquitous allergenic fungus. This response may contribute to the increasing prevalence of allergies and asthma.     

内生真菌链格孢菌醋酸乙酯提取物对金黄色葡萄球菌抑菌机制的研究

目的研究分离自药用植物白毛蛇Humata tyermanni的内生真菌链格孢菌发酵产物醋酸乙酯提取物(B06e)对金黄色葡萄球菌细胞膜完整性和通透性的影响。方法采用二倍稀释法测定B06e对金黄色葡萄球菌的最小抑菌浓度(MIC);测定B06e作用前后金黄色葡萄球菌培养液电导率,206、280 nm处吸光度(A)值的变化并结合流式细胞术研究B06e作用前后细胞膜通透性的变化。利用扫描电子显微镜(SEM)及傅里叶红外变换光谱(FT-IR)研究B06e对细胞膜结构的影响。结果 B06e对金黄色葡萄球菌的MIC为50μg/m L。3×MIC处理组的电导率是对照组的1.06倍;经B06e处理后,反应液的A260和A280值均显著高于对照组;3×MIC处理组的β-半乳糖苷酶活性是对照组的9.43倍;流式细胞仪分析表明3×MIC处理组被碘化丙啶(PI)着染的阳性细胞比例是对照组的47.63倍;SEM和FT-IR分析结果显示,B06e处理后,菌体细胞结构发生了损伤。结论 B06e能增强金黄色葡萄球菌细胞膜的通透性,破坏细胞膜的完整性,造成外源物质的大量流入和细胞质的大量外泄,从而使得菌体细胞内渗透压和代谢调控紊乱,最终导致细菌丧失生长繁殖的能力。     

Ungual phaeohyphomycosis caused by Alternaria alternata

Summary. Phaeohyphomycoses are a heterogeneous group of rare mycotic infections caused by dematiaceous fungi. They are classified into four forms: superficial, cutaneous and corneal, subcutaneous, systemic. Alternaria species are ubiquitous fungi that are occasionally aetiological agents of pheohyphomycosis. A case of onychomycosis caused by Alternaria alternata treated with itraconazole is reported.
Zusammenfassung. Phaeohyphomykosen sind eine heterogene Gruppe seltener, durch Dematiaceae-Arten hervorgerufener Infektionen Man unterscheidet vier Formen: oberflächliche, kutane und corneale, subkutane, systemische. Die Alternaria -Arten sind allgegenwärtige Pilze, die gelegentlich Phaeohyphomykosen verursachen. Wir berichten über einen Fall von Onychomykose, durch Alternaria verursacht und mit Itraconazol behandelt.     

90株互隔交链孢霉培养物的致突变性研究

90株互隔交链孢霉分别从林县地区(食管癌高发病区)和范县、商邱地区(食管癌低发病区)的粮食中分离。这些菌株培养物的乙醚提取物用E.coliND—160菌株检测其致突变性。其中66株提取物(73.3%)显示不同程度的致突变效应。这个结果提示互隔交链孢霉的产毒菌株广泛存在。林县地区粮食污染互隔交链孢霉的百分率远远超过其它二地区(P<0.001)。我们认为互隔交链孢霉的毒性代谢物可能对林县地区食管癌的发病率起着重要作用。本文还叙述和讨论了互隔交链孢霉的毒性代谢物。     

Nagel-Alternariose/Onychomycosis caused by Alternaria tenuis

Zusammenfassung: Ein Fall einer ungualen Alternariose bei einem 61jährigen Mann in Form einer Doppelinfektion mit Trichophyton rubrum wird vorgestellt. Alternaria tenuis (alternata) konnte mehrfach kulturell aus dem Nagehnaterial nachgewiesen werden. Andere Fälle über diese als opportunistisch anzusehende Infektion werden angeführt sowie differentialdiagnostische Aspekte diskutiert.
Summary: A case of uncommon ungual alternariosis in a 61-year-old man is presented. It resulted from a mixed infection with Trichophyton rubrum and Alternaria tenuis (alternata). Alternaria tenuis was repeatedly cultivated on agar. Other cases of opportunistic infection with alternaria species are mentioned. Differential diagnostic aspects are discussed.     

Cutaneous alternariosis in a cardiac transplant recipient

A 55-year-old male cardiac transplant recipient presented with cutaneous nodules on the limbs caused by Alternaria alternata. Oral fluconazole 200 mg daily for 3 weeks was ineffective. Itraconazole 100 mg oral daily was ceased when hyperglycaemia developed. Individual lesions were successfully treated with either curettage and cautery or double freeze-thaw cryotherapy. Alternaria spp. are ubiquitous fungal saprophytes which may cause cutaneous infections particularly in immunocompromised patients.     

Subcutaneous alternariosis

A case of subcutaneous alternariosis caused by Alternaria alternata is reported in a 52-year-old male who underwent kidney transplantation 1 year earlier. The infection manifested as a vegetating mass about 7 cm in diameter on the right forearm. Histological examination with Grocott staining and periodic acid-Schiff diastase revealed fungal spores and hyphae with chronic granulomatous inflammation. Biopsy fragments inoculated on Sabouraud-glucose agar with chloramphenicol produced colonies which were identified as Alternaria alternata on the basis of macroscopic and microscopic characters.     

互隔交链孢霉提取物261—B2—3在体外对DNA、RNA和蛋白质合成的影响

大多数化学致癌物均可影响DNA、RNA和蛋白质合成的过程。本文研究了从食管癌高发区林县粮食中分离出的互隔交链孢霉菌株261提取物261-B_2-3对这些大分子物质合成的影响。研究表明261-B_2-3对DNA和蛋白质的合成有明显的抑制,其作用强度呈明显的浓度相关性。但是它对RNA的合成无明显影响。三种大分子物质的合成对于261-B_2-3的敏感性顺序为:蛋白质>DNA>RNA。261-B_2-3对DNA和蛋白质抑制作用的类型和机理并不相同。在中止261-B_2-3的作用后,DNA的合成率持续下降,形成一谷值,属于模板损伤型,而蛋白质则呈递增型合成曲线,为干扰代谢型。261-B_2-3对大分子合成的干扰导致了细胞生物学和生化过程的紊乱,并有可能在诱变过程中起到一定作用。     

Assessment of Human Exposure to Five Alternaria Mycotoxins in China by Biomonitoring Approach

This biomonitoring study was conducted to investigate the concentration levels of five Alternaria mycotoxins in urine samples from 269 healthy volunteers living in the Yangtze River Delta, China. Alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA) and tentoxin (TEN) were detected in 38.3%, 48.7%, 63.9% and 23.4% of urine samples with the concentrations ranging from 0.057 to 45.8 ng/mL, 0.020 to 0.802 ng/mL, 0.050 to 80.6 ng/mL and 0.021 to 0.939 ng/mL, respectively. Altenuene (ALT) was not detected in any urine sample. Based on the urinary concentrations, the probable daily intake (PDI) values of Alternaria mycotoxins were calculated, and 100%, 99.2–100%, 0.372% and 1.12% of participants exceeded the threshold of toxicological concern (TTC) values for AOH, AME, TeA and TEN, respectively. This study revealed high potential health risks related to the contaminations of major Alternaria mycotoxins in China and highlighted the necessity for more toxicological studies to provide better basis for further comprehensive risk assessments.     

Onychomycosis caused by Alternaria spp. in Tuscany, Italy from 1985 to 1999

Cutaneous phaeohyphomycosis due to Alternaria spp. is reported with increasing frequency, especially in patients with immune deficiency. Onychomycosis caused by this mould is still rarely observed. Here we report nine cases observed in Tuscany in the period 1985-99; the agent was Alternaria alternata in eight cases and Alternaria chlamidospora in one. Diagnosis was made on the basis of repeated direct microscopic mycological examination and culture, confirmed by scanning electron microscope observation of fragments of colonies. In most cases, the clinical manifestations were dystrophy and distal subungual hyperkeratosis of one or two nails of the feet or hands. Seven cases were treated with oral itraconazole, successfully in six cases, as clinical and mycological recovery was confirmed at follow-up 1 year later.